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MAX483ESA+T中文资料

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .General DescriptionThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. The MAX483, MAX487, MAX488, and MAX489feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables,thus allowing error-free data transmission up to 250kbps.The driver slew rates of the MAX481, MAX485, MAX490,MAX491, and MAX1487 are not limited, allowing them to transmit up to 2.5Mbps.These transceivers draw between 120µA and 500µA of supply current when unloaded or fully loaded with disabled drivers. Additionally, the MAX481, MAX483, and MAX487have a low-current shutdown mode in which they consume only 0.1µA. All parts operate from a single 5V supply.Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-imped-ance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.The MAX487 and MAX1487 feature quarter-unit-load receiver input impedance, allowing up to 128 MAX487/MAX1487 transceivers on the bus. Full-duplex communi-cations are obtained using the MAX488–MAX491, while the MAX481, MAX483, MAX485, MAX487, and MAX1487are designed for half-duplex applications.________________________ApplicationsLow-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks__Next Generation Device Features♦For Fault-Tolerant ApplicationsMAX3430: ±80V Fault-Protected, Fail-Safe, 1/4Unit Load, +3.3V, RS-485 TransceiverMAX3440E–MAX3444E: ±15kV ESD-Protected,±60V Fault-Protected, 10Mbps, Fail-Safe, RS-485/J1708 Transceivers♦For Space-Constrained ApplicationsMAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,Profibus RS-485/RS-422 TransceiversMAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 PackageMAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422,True Fail-Safe ReceiversMAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,SOT23, RS-855/RS-422 Transmitters ♦For Multiple Transceiver ApplicationsMAX3030E–MAX3033E: ±15kV ESD-Protected,+3.3V, Quad RS-422 Transmitters ♦For Fail-Safe ApplicationsMAX3080–MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited RS-485/RS-422Transceivers♦For Low-Voltage ApplicationsMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited,True RS-485/RS-422 TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________Selection Table19-0122; Rev 8; 10/03Ordering Information appears at end of data sheet.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 2_______________________________________________________________________________________ABSOLUTE MAXIMUM RATINGSSupply Voltage (V CC ).............................................................12V Control Input Voltage (RE , DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (A, B)...................................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO).....................-0.5V to (V CC +0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW 8-Pin µMAX (derate 4.1mW/°C above +70°C)..............830mW 8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW 14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW Operating Temperature RangesMAX4_ _C_ _/MAX1487C_ A...............................0°C to +70°C MAX4__E_ _/MAX1487E_ A.............................-40°C to +85°C MAX4__MJ_/MAX1487MJA...........................-55°C to +125°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CDC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.V V IN = -7VV IN = 12V V IN = -7V V IN = 12V Input Current (A, B)I IN2V TH k Ω48-7V ≤V CM ≤12V, MAX487/MAX1487R INReceiver Input Resistance -7V ≤V CM ≤12V, all devices except MAX487/MAX1487R = 27Ω(RS-485), Figure 40.4V ≤V O ≤2.4VR = 50Ω(RS-422)I O = 4mA, V ID = -200mV I O = -4mA, V ID = 200mV V CM = 0V-7V ≤V CM ≤12V DE, DI, RE DE, DI, RE MAX487/MAX1487,DE = 0V, V CC = 0V or 5.25VDE, DI, RE R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4DE = 0V;V CC = 0V or 5.25V,all devices except MAX487/MAX1487CONDITIONSk Ω12µA ±1I OZRThree-State (high impedance)Output Current at ReceiverV 0.4V OL Receiver Output Low Voltage 3.5V OH Receiver Output High Voltage mV 70∆V TH Receiver Input Hysteresis V -0.20.2Receiver Differential Threshold Voltage-0.2mA 0.25mA-0.81.01.55V OD2Differential Driver Output (with load)V 2V 5V OD1Differential Driver Output (no load)µA±2I IN1Input CurrentV 0.8V IL Input Low Voltage V 2.0V IH Input High Voltage V 0.2∆V OD Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States V 0.2∆V OD Change in Magnitude of Driver Differential Output Voltage for Complementary Output States V 3V OC Driver Common-Mode Output VoltageUNITS MINTYPMAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________3SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)DC ELECTRICAL CHARACTERISTICS (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)ns 103060t PHLDriver Rise or Fall Time Figures 6 and 8, R DIFF = 54Ω, C L1= C L2= 100pF ns MAX490M, MAX491M MAX490C/E, MAX491C/E2090150MAX481, MAX485, MAX1487MAX490M, MAX491MMAX490C/E, MAX491C/E MAX481, MAX485, MAX1487Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pF MAX481 (Note 5)Figures 5 and 11, C RL = 15pF, S2 closedFigures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 6 and 8,R DIFF = 54Ω,C L1= C L2= 100pF Figures 6 and 10,R DIFF = 54Ω,C L1= C L2= 100pF CONDITIONS ns 510t SKEW ns50200600t SHDNTime to ShutdownMbps 2.5f MAX Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 103060t PLH 2050t LZ Receiver Disable Time from Low ns 2050t ZH Driver Input to Output Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low 2090200ns ns 134070t HZ t SKD Driver Disable Time from High |t PLH - t PHL |DifferentialReceiver Skewns 4070t LZ Driver Disable Time from Low ns 4070t ZL Driver Enable to Output Low 31540ns51525ns 31540t R , t F 2090200Driver Output Skew to Output t PLH , t PHL Receiver Input to Output4070t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERFigures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closedM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 4_______________________________________________________________________________________SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)3001000Figures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 5 and 11, C L = 15pF, S2 closed,A - B = 2VCONDITIONSns 40100t ZH(SHDN)Driver Enable from Shutdown toOutput High (MAX481)nsFigures 5 and 11, C L = 15pF, S1 closed,B - A = 2Vt ZL(SHDN)Receiver Enable from Shutdownto Output Low (MAX481)ns 40100t ZL(SHDN)Driver Enable from Shutdown toOutput Low (MAX481)ns 3001000t ZH(SHDN)Receiver Enable from Shutdownto Output High (MAX481)UNITS MINTYP MAX SYMBOLPARAMETERt PLH t SKEW Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFt PHL Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFDriver Input to Output Driver Output Skew to Output ns 100800ns ns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S2 closedt ZH(SHDN)Driver Enable from Shutdown to Output High2502000ns2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S1 closedt ZL(SHDN)Receiver Enable from Shutdown to Output Lowns 2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S2 closedt ZH(SHDN)Receiver Enable from Shutdown to Output Highns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S1 closedt ZL(SHDN)Driver Enable from Shutdown to Output Lowns 50200600MAX483/MAX487 (Note 5) t SHDN Time to Shutdownt PHL t PLH , t PHL < 50% of data period Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 100pF, S2 closed CONDITIONSkbps 250f MAX 2508002000Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 25080020002050t LZ Receiver Disable Time from Low ns 2050t ZH Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low ns ns 1003003000t HZ t SKD Driver Disable Time from High I t PLH - t PHL I DifferentialReceiver SkewFigures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFns 3003000t LZ Driver Disable Time from Low ns 2502000t ZL Driver Enable to Output Low ns Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFns 2502000t R , t F 2502000Driver Rise or Fall Time ns t PLH Receiver Input to Output2502000t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________530002.5OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGE525M A X 481-01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )1.515100.51.02.0203540450.90.1-50-252575RECEIVER OUTPUT LOW VOLTAGE vs.TEMPERATURE0.30.7TEMPERATURE (°C)O U T P U TL O W V O L T A G E (V )500.50.80.20.60.40100125-20-41.5 2.0 3.0 5.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGE-8-16M A X 481-02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )2.5 4.0-12-18-6-14-10-203.54.5 4.83.2-50-252575RECEIVER OUTPUT HIGH VOLTAGE vs.TEMPERATURE3.64.4TEMPERATURE (°C)O U T P UT H I G H V O L T A G E (V )0504.04.63.44.23.83.01001259000 1.0 3.0 4.5DRIVER OUTPUT CURRENT vs.DIFFERENTIAL OUTPUT VOLTAGE1070M A X 481-05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )2.0 4.05030806040200.5 1.5 2.53.5 2.31.5-50-2525125DRIVER DIFFERENTIAL OUTPUT VOLTAGEvs. TEMPERATURE1.72.1TEMPERATURE (°C)D I F FE R E N T I A L O U T P U T V O L T A G E (V )751.92.21.62.01.8100502.4__________________________________________Typical Operating Characteristics(V CC = 5V, T A = +25°C, unless otherwise noted.)NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICSNote 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to deviceground unless otherwise specified.Note 2:All typical specifications are given for V CC = 5V and T A = +25°C.Note 3:Supply current specification is valid for loaded transmitters when DE = 0V.Note 4:Applies to peak current. See Typical Operating Characteristics.Note 5:The MAX481/MAX483/MAX487 are put into shutdown by bringing RE high and DE low. If the inputs are in this state for lessthan 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 6___________________________________________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 5V, T A = +25°C, unless otherwise noted.)120008OUTPUT CURRENT vs.DRIVER OUTPUT LOW VOLTAGE20100M A X 481-07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )6604024801012140-1200-7-5-15OUTPUT CURRENT vs.DRIVER OUTPUT HIGH VOLTAGE-20-80M A X 481-08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )-31-603-6-4-2024-100-40100-40-60-2040100120MAX1487SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20608050020060040000140100-50-2550100MAX481/MAX485/MAX490/MAX491SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125100-50-2550100MAX483/MAX487–MAX489SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________7______________________________________________________________Pin DescriptionFigure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating CircuitM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487__________Applications InformationThe MAX481/MAX483/MAX485/MAX487–MAX491 and MAX1487 are low-power transceivers for RS-485 and RS-422 communications. The MAX481, MAX485, MAX490,MAX491, and MAX1487 can transmit and receive at data rates up to 2.5Mbps, while the MAX483, MAX487,MAX488, and MAX489 are specified for data rates up to 250kbps. The MAX488–MAX491 are full-duplex trans-ceivers while the MAX481, MAX483, MAX485, MAX487,and MAX1487 are half-duplex. In addition, Driver Enable (DE) and Receiver Enable (RE) pins are included on the MAX481, MAX483, MAX485, MAX487, MAX489,MAX491, and MAX1487. When disabled, the driver and receiver outputs are high impedance.MAX487/MAX1487:128 Transceivers on the BusThe 48k Ω, 1/4-unit-load receiver input impedance of the MAX487 and MAX1487 allows up to 128 transceivers on a bus, compared to the 1-unit load (12k Ωinput impedance) of standard RS-485 drivers (32 trans-ceivers maximum). Any combination of MAX487/MAX1487 and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481/MAX483/MAX485 and MAX488–MAX491 have standard 12k ΩReceiver Input impedance.Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 8_______________________________________________________________________________________Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating CircuitFigure 3. MAX489/MAX491 Pin Configuration and Typical Operating CircuitMAX483/MAX487/MAX488/MAX489:Reduced EMI and ReflectionsThe MAX483 and MAX487–MAX489 are slew-rate limit-ed, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 12 shows the dri-ver output waveform and its Fourier analysis of a 150kHz signal transmitted by a MAX481, MAX485,MAX490, MAX491, or MAX1487. High-frequency har-monics with large amplitudes are evident. Figure 13shows the same information displayed for a MAX483,MAX487, MAX488, or MAX489 transmitting under the same conditions. Figure 13’s high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________9_________________________________________________________________Test CircuitsFigure 4. Driver DC Test Load Figure 5. Receiver Timing Test LoadFigure 6. Driver/Receiver Timing Test Circuit Figure 7. Driver Timing Test LoadM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 10_______________________________________________________Switching Waveforms_________________Function Tables (MAX481/MAX483/MAX485/MAX487/MAX1487)Figure 8. Driver Propagation DelaysFigure 9. Driver Enable and Disable Times (except MAX488 and MAX490)Figure 10. Receiver Propagation DelaysFigure 11. Receiver Enable and Disable Times (except MAX488and MAX490)Table 1. TransmittingTable 2. ReceivingLow-Power Shutdown Mode (MAX481/MAX483/MAX487)A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled.In shutdown, the devices typically draw only 0.1µA of supply current.RE and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown.For the MAX481, MAX483, and MAX487, the t ZH and t ZL enable times assume the part was not in the low-power shutdown state (the MAX485/MAX488–MAX491and MAX1487 can not be shut down). The t ZH(SHDN)and t ZL(SHDN)enable times assume the parts were shut down (see Electrical Characteristics ).It takes the drivers and receivers longer to become enabled from the low-power shutdown state (t ZH(SHDN ), t ZL(SHDN)) than from the operating mode (t ZH , t ZL ). (The parts are in operating mode if the –R —E –,DE inputs equal a logical 0,1 or 1,1 or 0, 0.)Driver Output ProtectionExcessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short cir-cuits over the whole common-mode voltage range (see Typical Operating Characteristics ). In addition, a ther-mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.Propagation DelayMany digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 15–18 using Figure 14’s test circuit.The difference in receiver delay times, | t PLH - t PHL |, is typically under 13ns for the MAX481, MAX485,MAX490, MAX491, and MAX1487 and is typically less than 100ns for the MAX483 and MAX487–MAX489.The driver skew times are typically 5ns (10ns max) for the MAX481, MAX485, MAX490, MAX491, and MAX1487, and are typically 100ns (800ns max) for the MAX483 and MAX487–MAX489.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________1110dB/div0Hz5MHz500kHz/div10dB/div0Hz5MHz500kHz/divFigure 12. Driver Output Waveform and FFT Plot of MAX481/MAX485/MAX490/MAX491/MAX1487 Transmitting a 150kHz SignalFigure 13. Driver Output Waveform and FFT Plot of MAX483/MAX487–MAX489 Transmitting a 150kHz SignalM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 12______________________________________________________________________________________V CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CFigure 14. Receiver Propagation Delay Test CircuitFigure 15. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PHLFigure 16. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PLHPHL Figure 18. MAX483, MAX487–MAX489 Receiver t PLHLine Length vs. Data RateThe RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23.Figures 19 and 20 show the system differential voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 120Ωloads.Typical ApplicationsThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.Figures 21 and 22 show typical network applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23.To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possi-ble. The slew-rate-limited MAX483 and MAX487–MAX489are more tolerant of imperfect termination.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________13DIV Y -V ZRO5V 0V1V0V -1V5V 0V2µs/divFigure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable Figure 20. MAX483, MAX487–MAX489 System Differential Voltage at 110kHz Driving 4000ft of CableFigure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 NetworkM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 14______________________________________________________________________________________Figure 22. MAX488–MAX491 Full-Duplex RS-485 NetworkFigure 23. Line Repeater for MAX488–MAX491Isolated RS-485For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________15_______________Ordering Information_________________Chip TopographiesMAX481/MAX483/MAX485/MAX487/MAX1487N.C. RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND B N.C.V CCARE * Contact factory for dice specifications.__Ordering Information (continued)M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 16______________________________________________________________________________________TRANSISTOR COUNT: 248SUBSTRATE CONNECTED TO GNDMAX488/MAX490B RO 0.054"(1.372mm)0.080"(2.032mm)N.C. DIGND Z A V CCYN.C._____________________________________________Chip Topographies (continued)MAX489/MAX491B RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND Z A V CCYREMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________17Package Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)S O I C N .E P SM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 18______________________________________________________________________________________Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)MAX481/MAX483/MAX485/MAX487–MAX491Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________19©2003 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487P D I P N .E PSPackage Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)。

MAX典型电路演示文稿

第二十三页，共59页。
②控制字节的第5～7位为1～8片的片选或存贮器内的块地址选择位。此三个控制位用于选片或者内部块选择。标准的IIC规程允许选择16K位的存贮器。通过对几片器件或一个器件内的几个块的存取，可完成对16K位存贮器的选择，如表9-6所示。
表9-6 AT24CXX的A2A1A0
第二十四页，共59页。
CALL CACK
JB F0，WRNBYT MOV R0，#MTD ；有应答位，继而发数据，第一个数据为首址
第十七页，共59页。
WRDA： MOV A，@R0 LCALL WRB LCALL CACK ；检查ACK JB F0，WRNBYT1 ；无ACK INC R0 DJNZ R5，WRDA ；尚未发完n个字节，继续 LCALL STOP POP PSW RET
第十页，共59页。
9.2.2 软件IIC总线
假设单片机所用晶体振荡器的频率为6MHz。用P1.7和P1.6 分别模拟SDA和SCL，定义如下：
SDA
EQU P1.7
SCL
EQU P1.6
(1)
如果单片机则每个机器周期为2us,我们可分别写出产生时钟 SCL和SDA的发送起始条件和停止条件两段子程序如下。若晶振频率并非 6MHz，则要相应增删各程序段中NOP 指令的条数，以满足时序的要求。例如，若 fosc=12MHz ，则两条NOP指令应增至4条。
·假定控制字节已存放在片内RAM的SLA ·待发送数据各字节已位于片内RAM以MTD+1为起始地址的n个连续单元中。 ·NUMBYT ·接收到数据的存放首址存放在片内RAM的MTD单元。
WRNBYT： PUSH PSW WRNBYT1： MOV PSW，#18H ；改用第3

MAX491EESD+中文资料

Driver Input Voltage (DI).............................-0.5V to (VCC + 0.5V)
Driver Output Voltage (Y, Z; A, B) ..........................-8V to +12.5V
Receiver Input Voltage (A, B).................................-8V to +12.5V
元器件交易网
MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E
±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
ABSOLUTE MAXIMUM RATINGS
General Description
The MAX481E, MAX483E, MAX485E, MAX487E– MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environments. Each driver output and receiver input is protected against ±15kV electro-static discharge (ESD) shocks, without latchup. These parts contain one driver and one receiver. The MAX483E, MAX487E, MAX488E, and MAX489E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E are not limited, allowing them to transmit up to 2.5Mbps.

裸芯片种类

裸芯片种类裸芯片种类放大器：差动放大器AD629 AD8132 AD8351 AMP03 CA3026 INA117音频放大器LM1875 LM1876 LM2876 LM386 LM3875 LM3886 LM4766 LM4905 TDA1015 TTEA2025缓冲放大器HA0-5002HA0-5033HA-5002HAO-5033测量放大器AD524AD620AD622AD623AD624AD625AD627AMP02FSINA110INA111INA118INA122INA128INA128AINA129NA129AINA163INA2321INA321LTC6800 PGA203PGA206隔离放大器AD202AD210INA110ISO122对数放大器AD8317SL2524BTL441低噪声放大器CHA2090F100MA01502D功率放大器CA3020LM1875LM1876LM2876LM386LM3875LM3886LM4766LM4905MA08 509BTDA1015TTDA2822TGA2710TGA4505TGA4513TGA4517TGA4905可编程放大器AD526HA2400HA2405PGA103RF/IF放大器AD8351MC1550MC1590MCC1550采样-保持放大器AD585AAD684AD781HA0-5320LF198SHM-45MM可变增益放大器AD603AAD604SAD8367AD8369THS7530VCA810视频放大器AD813LM733LT1227TL592UA733C运算放大器AD515AD548AD549JAD644AD648AD704AD706AD708AD711AD712AD713AD741AD744AD746AD797AD8002AD8014AAD8033AD8034AD8042 AD8044AD8052AD8061AD8062AD8066AD8067AD8099AD811AD817AD820 AD822AD823AD824AD825AD828AD829AD844AD846AD847AD848AD849AD8513AD8541AD8552AD8602AD8605AD8620AD8651AD8672AD9617 AD9632AD OP07CA258CA3078CA3080CA3094CA3140CA3160CA3193CLC400 CLC449CLC501AMCHA0-2520HA0-2541HA0-2625HA0-5104HA2502HA2512HA -2515HA2522HA2525HA2529HA2540HA-2602HA2622HA2640HA2645HA-5102HA-5104HA5 130HA5142HAO-2540ICL7642ICL7650LF147LF153/LF353LF155LF156LF157LF347 LF351LF353LF356LF357LF411LF412LF441ALF442LF444LM107LM108LM108ALM118LM12LM124LM143LM1458LM148LM1556LM158LM301LM307LM308ALM324LM343LM346LM347LM348LM358LM432LM441LM675LM711LM715LM7171LM725LM741LM747LM759LM833LMC6034LMC6082LMH6624LMH6702LMV824LT1008LT1012CLT1013LT1014LT1055LT1057CLT1494LT1495LT1803LT1880LT6233LTC1052MA01MAX4020MAX407 MAX4385EMAX4472MAX492MAX495MC1456MC1536MC1537MC1556MC33 03MC33171MC3503MC4741MCC1536MSK103NE5532OP07GBCOP07GRBCOP07NBCOP09 OP11GBCOP11GRBCOP11NBCOP17OP177OP17NBCOP191OP196OP200OP213OP215 OP220NBCOP2228OP227OP249OP260OP262OP27OP270OP270GBCOP277 OP279OP27GBCOP27NBCOP282OP282GBCOP284OP284GBCOP285OP291OP2 97GBCOP37NBCOP400GBCOP4177OP420OP4227OP42NBCOP467GBCOP470OP471O P471GBCOP482OP482GBCOP484OP491OP491GBCOP497OP727OP747OP77OP777 OP77NBCOP90OP97NBCOPA111OPA128OPA132OPA177OPA2132OPA2227OPA2228 OPA227OPA228OPA2350OPA241OPA2541OPA2658OPA277OPA335OPA4134O PA4227OPA4234OPA4277OPA445OPA541OPA544OPA547OPA548OPA549OPA551OPA 552OPA602OPA606OPA620OPA627OPA643OPA704OPA727PA76RC3078RC4136 RC4558TCA0372THS4021THS4082TL061TL064TL071TL072TL081TL082TL084TLC2264TLC2274TLC274TLC27L4TLC27L9TLC4501TLE2021CTLE2027TLE2 064TLE2072TLE2074TLE2082TLE2161TLE2662TLV2211TLV2254TLV2324TLV2442TL V2764UA709电压比较器LM111LM119LM139LM1414LM1514LM161LM193LM2901LM2903LM306 LM311LM319LM339LM361LM393LM710LMV393LMV7235LMV7239LMX393 LT1713ILT1721MAX900MAX903MAX9030MAX909MAX9109MAX912MAX913 MAX921MAX923MAX975MAX998MC1414MC1514MC34074MCC1514RC1414TLV3492 TSM109(A)电压跟随器LM102LM110LM210LM310电源管理：电压调节器可调输出调节器LM133LM137HLM137KLM138LM150LM2576ADJLM317HLM317KLM337HLM3 37KLM338LM350LM396LM723LMV431LT1033LT1038SVR1038TLV431AUA723C UC1033KUC117UC137UC150KUC337BUCK（降压斩波）调节器LM2672 LM2674LM2675LM2676LM2677LT1076固定输出调节器78057809781278157905791278L1278M05C78M06FSC78M0978M1878T1279L0979M0579M0679M1279M1579M15FSCKA78M10KA7906 LM109KLM2576-12LM2576-5LM309KLM320-12LM320-15LM320-5LM323LM3 40-15LM7812LM78L09LM78L12ACLM79L09LM79M05LM79M12LM79M15MC7812ACMC78 M18MC78M24UA78L09AUA78M10UA79M15UC7812低压差调节器ADP3338-5AME8805DEGTLM1084I-ADJLM1085LM1085I-ADJLM1117-1.8LM1117-ADJLM2936LM2940-15LM2940-5LM2941LM2990-15LM2991LMS1587-3.3LMS8117ALMS8117A-1.8LP2950LP2951ALP2980-5LP2985A-5.0LP2985AI-2.5LP2985LT1083LT1084-12LT1085CLT1086HLT1086KCLT1175LT1185 LT1581-ADJLT1763LT1764MAX1818MAX604MAX883MIC29150MIC29152MIC29300-5.0MI C29302MIC2941A-ADJMIC29500-3.3MIC29500-5.0MIC29502MIC29750-3.3MIC29750-5.0MIC29752 MIC5201MIC5219-5.0MSK5012MSK5150RC1117RC1584RC1585RC1587TPS7301QTPS73HD318可编程调节器ICL7663MAX663MAX664MAX666开关调节器ADP1111ADP3000ADP3050T1074PWM控制LT1526MAX1993MC3406SG1526TL494TL598TOP222YUC1526UC1843UC1846 UC1863UC2825AUC2843UC2846UC3524UC3525AUC3526UC3526AUC3825AU C3840UC3842UC3843UC3845UC3846UC3851UC3856UCC1800UCC1805UCC1806UC C1846UCC2580UCC2805UCC3580-1UCC3581UCC3801UCC3802UCC3803UCC3805UC C3808UCC3808UCC3810UCC3850-1UCC38C40DC-DCAD536AD636JAD637SADP2105HAT2099LTC3414LTC3416MAX762MAX764MC3 4063MX636PM7224GBCRMS-DC变换器AD536AD636JAD637SMX636电压-电流变换器XTR110AG电压变换器ICL7660ICL7662电压基准LM113MD8LM129LM136-5.0LM199LM329LM336-2.5LM336-5.0LM385-2.5LM399LM4040LM4050A-10LM4050A-4.1LT1031CDMAX6065MAX6125MAX6143MAX 6176MAX6220MAX6241MAX6325MAX6350MAX674REF01REF02REF05REF101REF102REF195TL1431 TL431A马达控制MC33035MCC33035ML4425UC3625UC3637UC3638存储器：快闪存储器(FLASH)K8D6316UBMK9F28080U0CK9F2808U0CMT28C6428P18MT28F128J3FSMT28F 400B5BQ48AMT28F642D18SST39LF100SST39VF080SST39VF1681TMS29F040X76F100随机存取存储器(RAM)IDT6116SAUIDT7026IDT7164IS61LV12816LIS61LV5128ALK4H561638DK6R4008 CIDK6R4016V1DMK68345MT28C6428P18SMJ44C251BSTK12C68STK20C04X20C04只读存储器(ROM)IS93C66M27C1001M95640TMS27PC128X24C04X28C64X5045X84641数据变换：模数转换器(ADC)14433 AD9048AD1674AD537AD571SAD573AD574AD674AD7555AD7575AD7671AD7723AD7864AD7870AD7875AD7876AD7889AD7892AD7893AD789 5AD9012AD9040AD9040AAD9042AD9048AD9050AD9058AD9200AD9203AD92 40AD9260ADC0801ADC0802ADC0803ADC0804ADC0808ADC0820ADC0844ADC0 848ADC12081ADC500BMMADC674ADC825MMADS574SADS774ADS7852ADS7864ADS805A DS8342CA3318DDC112UICL7107ICL7109LTC1608MAX162MAX170CMAX189MAX192MAX195 MC14433TC7107THS1206THS1207TLC2543ZN447ZN449数模转换器(DAC)AD390AD396KAD5320AD5321AD5424AD5433AD5541AD558AD561JAD565 AD664AD667AD7224AD7245AD7247AD7520AD7521AD7533AD7534AD7538 AD7541AD7542AAD7545AD7547AD9742AD9760CA3338DAC08DAC0800DAC0830DAC0832DAC1208DAC1210DAC1218DAC1219DAC1230DAC4813DAC4815DAC 7724DAC8412DAC8562DAC-HZ12BMMMAX197MAX5201MAX530MAX5721MX7224MX7534 J/D数据采集系统AD363AD7716AD7874AD7890AD7891AD974MAX125压频(V/F)和频压(F/V)转换AD650ALM2917VFC32分立器件：二极管雪崩二极管BYV26B限流二极管CD5302快恢复二极管1N54181N581125F10030BF2030BF40CPD25FR104FR107FR604MUR1100 MUR120MUR130MUR410MUR460MURB1620CTMURC1520MURC1540MURC 1560MURC410MURC415MURC420MURC460MURC820MURS120US1M锗二极管1N60低漏电流二极管XPAD10PIN二极管5082-00015082-0012MA4P160-134整流二极管1N40011N40021N40041N40061N40481N47201N47221N54011N54811N5625 CD483GL34DHSMS2820肖特基二极管1N57111N58181N58201N582230CLJQ100B340LABAS70BAT54CD5711CP108 CPD77HSCH-5331MBR0520MBR10100MBR1545MBR20200MBR2060MBR253 5MBR3100MBRC1060MS1045MS16100MS1680MS8100SB360SB540SB560SBL1640SC036H100S5BS C060S045ASC070H045ASC070H150ASC105H045ASC105H100ASC105S030ASC105S060AS C125H100SSC125S060ASC125S060SSC200S0308SC200S045SSC275H100SSC275S030SSC275S050S5B开关二极管1N36001N41481N41531N914BAS16BAS21BAV21BAV70BAV99BAW56CD4150CD4153瞬态电压抑制二极管(TVS)1.5KE18ACD1.5KE39CA1.5KE400A1.5KE47C1.5KE82A变容二极管BB132BBY40MC100EPT20齐纳二极管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双极晶体管(BJT)：达林顿晶体管2N62842N62872N6533BD651BDV65BCP117CP517MJ10007MJ11015MJ11016 MJD122TIP122TIP127TIP137TIP142ZTX603NPN型晶体管2C2222A2N16132N2219A2N22222N2222A2N2369A2N24842N29202N30192 N33022N34182N34402N35842N37162N37172N37712N3866A2N39042N39462N394 72N39612N41302N42402N50312N50382N51092N53012N53022N53302N5331 2N54862N55512N55842N56292N58852N58862N62702N62732N63542N6373 2N64312N64962N64972N65152N67182N7082N90132N9182N930AT381AT387BC441BC817BC846BCX5616BF258BF620BF622BFG591BFQ18ABFR183BFR90ABFR92ABFR93BFS20BU406BU508ABUR52BUW45BUW45 BUX98ACP310FCX493FJA13009FMMT491FMMTA42XCWKSC2258AKSC2330KS C5027KSC5042LM114LM194LM394MAT01MAT02MJ13015MJ15024MJ16110MJE13009MJE1 80MJW16018MMBT3904MPSA05MPSA43MRF4427MRF581MRF951MRFC581PN 3568PNP型晶体管2C2907A2N15362N21432N27932N2905A2N2907A2N36362N37992N38672N3 9062N40332N40362N42092N53792N54012N54162N56802N62112N62132N6420 2N64212N64233N108BC461BC557BC558BFT92BSR12BUW22CP608CP710D45H11KSA1304MJ15012MJD350MJE170MJE5172MJEC15029MJEC350 MMBT3906MMBTH81MPSA93MPSA94PN4258S9015TIP32C结型场效应晶体管(JFET)：N沟道2N38232N41182N42212N43382N43912N43922N4416A2N54342N54572N548 42N59022N59052N59062N59112N5912ATF13100J106MPF4392NE321000NE32 400NE32500SST108U310P沟道MMBFJ177SST177绝缘栅效应晶体管(MOSFET)：N沟道2N66602N66612N67662N67962N70022N7002E2N72252N72682N72692N739 4APT6060NDBLF244BLF246BS107ABSS138DAFDH27N50FDW2520CFQD13N06F QD2N60FQD6N40CFQP13N06FQP13N10FQP19N20CPWDFQP2N60CFQP33N10PWDFQP5N50CFQ PF16N15FQPF2N60CFQPF3N60HUF75639P3IRCC130IRF1405LPBFIRF151IRF3706SIRF5NJ3315IRF5NJ540IRF5NJZ48IRF7452I RF7456IRF7811IRF7812IRF7828IRF840IRFB4310IRFBG20BVIRFBG30IRFC014BIRFC024NBIRFC0 48NBIRFC110IRFC110BVIRFC11N50ABIRFC120BVIRFC120NBIRFC130IRFC130BIRFC130BVIRF C130NBIRFC1310NBIRFC13N15DIRFC140BVIRFC140NBIRFC150IRFC150BIRFC18N15DIRFC210IRFC210BIRFC220 BVIRFC22N50AIRFC230IRFC230BIRFC230BVIRFC240IRFC250BIRFC250NBIRFC260NBIRFC2807VIRFC3315BIRFC360IRFC3710IRFC3710BVIRFC3810BIRFC3815BVIRFC420IRFC430IRFC430BIRFC430BVIRFC43 N50KIRFC440IRFC440BVIRFC450IRFC450BVIRFC460IRFC52N15DBIRFC530BIRFC540IRFC540BIRFC90N2 0DIRFCF30IRFCF30BIRFCF50IRFCF50BVIRFD010BVIRFM250IRFP2907ZPBFIRFPS38N60LIRFS9N60AI RHF7230IRL5NJ7413IRLC2203IRLC2203NBIRLC240BIRLC2803IRLC3215IRLMS2002IXFB70N60IXFH58N20IXFH 74N20IXFH80N20IXFK64N60PIXFN80N50PIXKK85N60CJANTX2N7225LND150MMFT2406T1MMFT6661TMPF 6661MRF281MRF282MRF284MTB3N120EMTD6N10MTP10N10MTP3055MTP75N05HDPD57006SPD57060S PTF10045PTF10135PTF210451RFG70N06SD203SD211SD215SD303SD306SD5000SI7922SPP07N60C3SPW20N 60C3SST215STD1NC60C-1STD2HNK60ZSTD2NC60C-1STP9NC65SUP60N06VMP4VN 2001VN2010VN2222VN3515VN4012VN66VNDQ3CHPWFP640XSD211P沟道2N68492N7426BS250BSS84FDC5614FDW2520CFQP17P10FQPF6P25IRF7325IRF7329IRF9510IRFC4905BVIRFC5210BIRFC5210BVIRFC7416BIRFC7604IRFC9014IRFC9 014BVIRFC9024NBIRFC9110BVIRFC9120BVIRFC9130IRFC9130BVIRFC9130NIRFC9130NBIRFC9140BIRFC9140B VIRFC9220IRFC9220BIRFC9220BVIRFC9240IRFC9634IRFD9010BVIRFP9150IRHM9160IRHM9250IRHM9260IRHNA9260IXTH11P50SFH9154SI2301DSVP0300异质结晶体管NE321000NE32400NE32500金属半导体晶体管MWT-16PHMWT-7H绝缘栅双极晶体管(IGBT)IRG4CC50FBIRG4CC50UIRGB15B60KBIRGC25B120KIXBH9N160G可控硅(SCR)2N2324BT151晶体管阵列：达林顿MC1413ULN2002ULN2003AULN2004AULN2023ULN2803 MOSFETTPIC2701VQ3001BJTCA3045CA3081CA3096LM3045MC3346逻辑电路：加法器5428354LS28354LS83CD4008BSN74283算术逻辑部件54HC181双向开关CD4016BCD4066B缓冲器5433543854405438544054C24454F24454HC12654HC24454HCT36554LS0654LS0754LS12654LS24454LS2874HC24474LS0674LS12674LS24474LS28 74LS36774LS3774LS3874S14074S244CD4049UBCD4050BCD4502BCD4503NC7 NZ34K8XSN74HC244计数器549054925492549374935416054161541975439054LS925416054161A54925493A54AC39054F16154F161A54FCT16154HC16354HC192 54HC19354HC404054HCT16154HCT16254HCT1954HCT39354LS16054LS1615 4LS16254LS16354LS19054LS19254LS19354LS19654LS19754LS29054LS29354LS39354LS59054 LS59054LS9054LS9254LS9354S16354S1967493A74HC19174HC401774HC404074LS1 6074LS16174LS16274LS19074LS19174LS19274LS19374LS19674LS19774LS29374 LS39074LS39374LS9074LS9274LS9374S196CD40102BCD40110BCD40163BCD4017C D40193BHCD4022BCD4024BCD4029BCD4040BHCD4045CD4059ACD4060BCD4510BCD4 516BCD4520BCD4522BCD4526DM74LS393DM74LS90MC14522BMC14569SP8743译码器54ACT13854HC13854HC13954HC23854HCT15454LS1354LS13854LS14554LS15454LS24754LS24854LS4254LS4854LS4974HCT15474LS13874LS14574LS15474LS24774LS 24874LS4274LS4774LS48编码器54C92254C92354HC14754HCT14754LS14754LS14874C92274LS14774LS148AD V7176MM54C922触发器547254735476541095472FSC5473547654AHCT7454ALS57454F11254F27354F7454FCT57454H7454HC10754HC11254HC17554HC27354HC7454H CT11254HCT7454L7354LS10754LS11254LS11354LS17554LS57454LS7354LS7654S11 254S7474FCT57474HC11274HC27374HC7474LS10974LS11274LS11374LS27374 LS37474LS7374LS7474S74CD4013BCD40174BCD4027BMCC74HC107SN74157SN741 75门电路5400540154035404540554065407540854085409 54105410542054215425542754305450546054AC0054ACT0054ACT8654AS0854F0254F8654H0054H0154H0154H2054H2154H2254H4054H5254H5554HC0054HC0154HC1154HC13254HC2054HC32 54HCT0354HCT2054HCT8654L2054LS0054LS0154LS0354LS0854LS0954LS10 54LS1154LS13354LS2054LS2154LS2654LS26054LS26054LS26054LS2754LS30 54LS3254LS3754LS38654LS4054LS8654S0054S0854S0954S1054S14054S2054S327400740474057409741074AC0074AC1108674HC0074HCT0074HCT0374LCX084LS0074LS0474LS0874LS1074LS1374LS13274LS21 74LS2674LS26074LS3074LS3274LS38674LS86A74S004S0874S10CD4000BCD4001BCD4002BCD4011BCD4012BCD4019CD4019BCD4023BCD4025BCD403 0BCD4068BCD4070BCD4071BCD4073BCD4077BCD4081BCD4082BDM74AS00DM74AS08DM74LS00DM74LS04DM74LS08DM74LS86MC10107MC10505MC5440FMCC10H107MCC74LS86MI C320MPY54LS27NC7SZ08SN7440SN74LVC2G38反相器541454AHCT1G0454F0454HC1454HCT1454LS0454LS0554LS1454LV047414 74F0474HCT0474LS0574LS14CD4007UBCD4069UBCD4502BDM74ALS04BDS7 812MM74HC04NL27WZ14SN74LVC2G14锁存器54755411654116547554ALS573C54F37354F57354HC53354HC57354HCT373 54HCT57354LS37354LS57354LS7554LS7774ALS57374HC57374HCT573A74LS3 7374LS57374LS7574S196CD4508BCD74HC75寄存器5416414557B45575416454194541995429854HC16454HC59554HCT16454HCT29954LS16454LS19554LS29554LS39554LS9554LS9654S19474HC59574L S16474LS16574LS29574LS29974LS395CD4015BCD40194BCD4021BCD4034BCD4035BCD4094BCD4517BCD4557BCD4562BHEF4557BMC14557MC14562MCC14557BMPY54LS 164SN74194施密特触发器74HC14ACS14DMSRCD40106BCD4093BMC14584MCC14584B数值比较器54LS8574LS68874LS85CD4063BCD4585B多谐振荡器541215412354C22154HC12354HC22154HCT22154LS12254LS12354LS22154S1 2374HC22174LS12274LS12374LS221CD14538CD4047BCD4098BCD4528BCD453 8BMC14528奇偶校验5418074LS280可编程逻辑器件(PLD)GAL16V8DGAL20V10GAL20V8BGAL22V10ISPLSI1032ISPLSI1048PEEL22CV10AX C95144XC9536XC9572-15PC模拟开关和多路转换器：模拟开关AD7510AD7511AD7512ADG201ADG202ADG212AADG222BADG411ADG412A DG413ADG419ADG433ADG436ADG442DG190DG201ADG300ADG301ADG303DG303 ADG307DG307ADG307BDG308ADG403DG405DG411ADG412DG413DG442HI-201HI-5043HI-5051ISL43141MAX313C/DMAX314MAX319MAX333MAX333 AMAX352MAX4066C/DMAX4516C/DMAX4610MAX4622MAX4657MAX4658MAX4660M AX4662NLAS2066多路转换器54298AD7501JAD7503AD7506AD9300ADG506ADG507ADG526AADG706ADG 732CD4051BCD4052BCD4053BCD4067DG408DG458DG506ADG508AHCF4053MA X308MAX336MAX396MAX4519MC10174MC10574MC54HC75JMCC10174HI-548HI 0-0509HI0-506HI-509HI-50854ACT25154HC15754HC406754LS29874ACT15374LS35774VHC4 051多路分配器54HC13854HC13954HC406754HCT15454LS1354LS13854LS15474HCT15474LS 13874LS154CD4051BCD4052BCD4053BCD4067HCF4053光电器件：光耦合器4N244N486N1366N137FND400HCPL-5231ILQ55JANTX4N48MOC3063光敏二极管SP101-400微控制器：AT89C51AT89C52AT89S51AT89S52AT89S8253AT91FR40162P87C528GBLKAAT8 0C31X2P87C591P89V51TS80C32X2TSC87C52W77E58W78E54B接口电路：总线收发器82C87DS36C278ISO422MAX3318MAX3486MAX485MAX488MAX490SN75160 SN75162SP485接收器82C5082C5182C52DS26LS33CDS7820DS9637DS96F173ICL232MAX232MAX23 3MAX238MAX243总线控制器MD82188驱动器DS96F174MAX232MAX233MAX238MAX243驱动器：全桥驱动器HIP4080HIP4081HIP4086IRS2453DL6203MOSFET驱动器ICL7667IR2104IR2110CIR2113CIR2130CIR2135IR2213IR2214LM5112MIC4420 MIC4423MIC4424MIC4426MIC4428MIC4429MIC4469TC4423功率驱动器UC1708UC3707UC3708其余部分：有源滤波器MAX253MAX274MAX293MAX297S3528BS3529UAF42数字信号处理（DSP）SMJ320C40TMS320F240乘法器AD534KAD632ICL8013MC1594锁相环CD4046BHPE3236传感器ADXRS150ADXRS300ADXRS401LM20LM335ALM335A信号调节器AD598AD698NE5521SE5521定时器54LS29482C54CD4541BICM7555ICM7556LM555LM556MC14541NE555NE556振荡器74S124ICL8038LTC6906调制解调器LM1596MC14544MC34115MC3517TCM3105。

MEMORY存储芯片MAX491EESD+T中文规格书

μMAX
8 VCC 7B 6A 5 GND
8A
RO 1
R
RE 2
DE 3
DI 4 D
8 VCC 7B
Rt 6
A
5 GND
MAX481 MAX483 MAX485 MAX487 MAX1487
DE
DI D B Rt
A R
RO
7 GND
RE
6 DI
5 DE
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH. TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.
MAX481/MAX483/MAX485/ MAX487–MAX491/MAX1487
Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
______________________________________________________________Pin Description
Figure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating Circuit
7
MAX481/MAX483/MAX485/ MAX487–MAX491/MAX1487
Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
8
__________Applications Information

许继系列保护调试经验汇总

800系列保护调试经验汇总1．调试时对保护的各项功能定值不能只测试一点，应取多点，才能发现问题。

比如我在调试过流反时限时曾遇到：当定值按1A整定时，出口时间正确；当定值整定为其他定值后，时间不正确。

后经过修改程序解决。

（李书圣）2．报A/D自检错应检查CPU板5V，15V电源，其次检查自检芯片5V是否正常，检查CPU管脚是否虚焊或粘连以及DSP启动A/D脚是否断线及重新烧CPLD程序或更换CPLD。

（李书圣）6．需注意数据线地址线及芯片管脚粘连虚焊现象多发。

（李书圣）7．保护硬压板采用强电开入220V或110V，节省外部转换光耦成本。

在装臵通过电阻串联和并联降压后（1.8V左右）直接开入光耦。

需要注意的问题是开入电压为多少时，CPU感受不到开入变位，应该是额定电压的50％~70％。

（李书圣）8．在传完程序后经常会出现保护模块通讯时好时坏的现象，多数情况都是因为背板上用以调节通讯的跳针未打至ON的状态。

因此提醒大家注意：调试前一定要先检查一下各保护插件及背板上调节用的开关或跳针的位臵是否正确。

（张又君）保护模块有时候通信不上，可能是背板上LON网通信用的匹配电阻跳针位臵没有打对，应短接靠近电阻那一侧的跳针。

背板上有一个LON网匹配电阻。

它的旁边也有一个跳针，分RUN位和OFF位。

我们应该将它打到RUN位置，即靠近电阻的一侧。

否则，将影响CPU的正常通信。

9．在出现保护模块通讯不上的情况时，可观察LON网指示灯是否正常。

正常情况下，如没有保护程序，LON网指示灯应慢闪，在有保护程序时，LON网指示灯不亮。

若无LON网程序指示灯则常亮。

经常出现明明有LON网程序而指示灯常亮的情况，此类情况多数是LON座焊接不合格所致。

（张又君）10．由于变压器、发变组800系列保护装臵集成了出口的功能，所以在调试过程中，要注意测试出口继电器的电流保持功能。

（保持电流自适应，无规格限制）（张又君）12．差动保护中新增了TA饱和的判别功能，调试过程中，要注意测试。

MEMORY存储芯片MAX481ECPA+中文规格书

±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers Supply Voltage (V CC ).............................................................12V Control Input Voltage (–R —E –, DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (Y, Z; A, B)..........................-8V to +12.5VReceiver Input Voltage (A, B).................................-8V to +12.5VReceiver Output Voltage (RO)....................-0.5V to (V CC + 0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW 14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW Operating Temperature Ranges MAX4_ _C_ _/MAX1487EC_ A.............................0°C to +70°C MAX4__E_ _/MAX1487EE_ A...........................-40°C to +85°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°C DC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.ABSOLUTE MAXIMUM RATINGS PARAMETER SYMBOL MIN TYP MAX UNITS Driver Common-Mode OutputVoltageV OC 3V Change in Magnitude of DriverDifferential Output Voltage forComplementary Output StatesΔV OD 0.2V Change in Magnitude of DriverCommon-Mode Output Voltagefor Complementary Output StatesΔV OD 0.2V Input High VoltageV IH 2.0V Input Low VoltageV IL 0.8V Input Current I IN1±2µA Differential Driver Output (no load)V OD15V 2V Differential Driver Output(with load)V OD2 1.551.0-0.8mA 0.25mA -0.2Receiver Differential ThresholdVoltage-0.20.2V Receiver Input HysteresisΔV TH 70mV Receiver Output High VoltageV OH 3.5Receiver Output Low VoltageV OL 0.4V Three-State (high impedance)Output Current at Receiver I OZR ±1µA 12k ΩCONDITIONS DE = 0V;V CC = 0V or 5.25V,all devices exceptMAX487E/MAX1487ER = 27Ωor 50Ω, Figure 8R = 27Ωor 50Ω, Figure 8R = 27Ωor 50Ω, Figure 8DE, DI, –R —E –MAX487E/MAX1487E,DE = 0V, V CC = 0V or 5.25VDE, DI, –R —E –DE, DI, –R —E–-7V ≤V CM ≤12V V CM = 0V I O = -4mA, V ID = 200mV I O = 4mA, V ID = -200mV R = 50Ω(RS-422)0.4V ≤V O ≤2.4VR = 27Ω(RS-485), Figure 8-7V ≤V CM ≤12V, all devices except MAX487E/MAX1487EReceiver Input Resistance R IN-7V ≤V CM ≤12V, MAX487E/MAX1487E 48k ΩV TH I IN2Input Current (A, B)V IN = 12V V IN = -7V V IN = 12V V IN = -7V V MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E2±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 TransceiversFigure 26. MAX488E–MAX491E Full-Duplex RS-485 NetworkFigure 25. MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E Typical Half-Duplex RS-485 NetworkMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E15。

MAX487ESA中文资料

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .General DescriptionThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. The MAX483, MAX487, MAX488, and MAX489feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables,thus allowing error-free data transmission up to 250kbps.The driver slew rates of the MAX481, MAX485, MAX490,MAX491, and MAX1487 are not limited, allowing them to transmit up to 2.5Mbps.These transceivers draw between 120µA and 500µA of supply current when unloaded or fully loaded with disabled drivers. Additionally, the MAX481, MAX483, and MAX487have a low-current shutdown mode in which they consume only 0.1µA. All parts operate from a single 5V supply.Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-imped-ance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.The MAX487 and MAX1487 feature quarter-unit-load receiver input impedance, allowing up to 128 MAX487/MAX1487 transceivers on the bus. Full-duplex communi-cations are obtained using the MAX488–MAX491, while the MAX481, MAX483, MAX485, MAX487, and MAX1487are designed for half-duplex applications.________________________ApplicationsLow-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks__Next Generation Device Features♦For Fault-Tolerant ApplicationsMAX3430: ±80V Fault-Protected, Fail-Safe, 1/4Unit Load, +3.3V, RS-485 TransceiverMAX3440E–MAX3444E: ±15kV ESD-Protected,±60V Fault-Protected, 10Mbps, Fail-Safe, RS-485/J1708 Transceivers♦For Space-Constrained ApplicationsMAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,Profibus RS-485/RS-422 TransceiversMAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 PackageMAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422,True Fail-Safe ReceiversMAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,SOT23, RS-855/RS-422 Transmitters ♦For Multiple Transceiver ApplicationsMAX3030E–MAX3033E: ±15kV ESD-Protected,+3.3V, Quad RS-422 Transmitters ♦For Fail-Safe ApplicationsMAX3080–MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited RS-485/RS-422Transceivers♦For Low-Voltage ApplicationsMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited,True RS-485/RS-422 TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________Selection Table19-0122; Rev 8; 10/03Ordering Information appears at end of data sheet.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 2_______________________________________________________________________________________ABSOLUTE MAXIMUM RATINGSSupply Voltage (V CC ).............................................................12V Control Input Voltage (RE , DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (A, B)...................................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO).....................-0.5V to (V CC +0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW 8-Pin µMAX (derate 4.1mW/°C above +70°C)..............830mW 8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW 14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW Operating Temperature RangesMAX4_ _C_ _/MAX1487C_ A...............................0°C to +70°C MAX4__E_ _/MAX1487E_ A.............................-40°C to +85°C MAX4__MJ_/MAX1487MJA...........................-55°C to +125°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CDC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.V V IN = -7VV IN = 12V V IN = -7V V IN = 12V Input Current (A, B)I IN2V TH k Ω48-7V ≤V CM ≤12V, MAX487/MAX1487R INReceiver Input Resistance -7V ≤V CM ≤12V, all devices except MAX487/MAX1487R = 27Ω(RS-485), Figure 40.4V ≤V O ≤2.4VR = 50Ω(RS-422)I O = 4mA, V ID = -200mV I O = -4mA, V ID = 200mV V CM = 0V-7V ≤V CM ≤12V DE, DI, RE DE, DI, RE MAX487/MAX1487,DE = 0V, V CC = 0V or 5.25VDE, DI, RE R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4DE = 0V;V CC = 0V or 5.25V,all devices except MAX487/MAX1487CONDITIONSk Ω12µA ±1I OZRThree-State (high impedance)Output Current at ReceiverV 0.4V OL Receiver Output Low Voltage 3.5V OH Receiver Output High Voltage mV 70∆V TH Receiver Input Hysteresis V -0.20.2Receiver Differential Threshold Voltage-0.2mA 0.25mA-0.81.01.55V OD2Differential Driver Output (with load)V 2V 5V OD1Differential Driver Output (no load)µA±2I IN1Input CurrentV 0.8V IL Input Low Voltage V 2.0V IH Input High Voltage V 0.2∆V OD Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States V 0.2∆V OD Change in Magnitude of Driver Differential Output Voltage for Complementary Output States V 3V OC Driver Common-Mode Output VoltageUNITS MINTYPMAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________3SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)DC ELECTRICAL CHARACTERISTICS (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)ns 103060t PHLDriver Rise or Fall Time Figures 6 and 8, R DIFF = 54Ω, C L1= C L2= 100pF ns MAX490M, MAX491M MAX490C/E, MAX491C/E2090150MAX481, MAX485, MAX1487MAX490M, MAX491MMAX490C/E, MAX491C/E MAX481, MAX485, MAX1487Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pF MAX481 (Note 5)Figures 5 and 11, C RL = 15pF, S2 closedFigures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 6 and 8,R DIFF = 54Ω,C L1= C L2= 100pF Figures 6 and 10,R DIFF = 54Ω,C L1= C L2= 100pF CONDITIONS ns 510t SKEW ns50200600t SHDNTime to ShutdownMbps 2.5f MAX Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 103060t PLH 2050t LZ Receiver Disable Time from Low ns 2050t ZH Driver Input to Output Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low 2090200ns ns 134070t HZ t SKD Driver Disable Time from High |t PLH - t PHL |DifferentialReceiver Skewns 4070t LZ Driver Disable Time from Low ns 4070t ZL Driver Enable to Output Low 31540ns51525ns 31540t R , t F 2090200Driver Output Skew to Output t PLH , t PHL Receiver Input to Output4070t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERFigures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closedM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 4_______________________________________________________________________________________SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)3001000Figures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 5 and 11, C L = 15pF, S2 closed,A - B = 2VCONDITIONSns 40100t ZH(SHDN)Driver Enable from Shutdown toOutput High (MAX481)nsFigures 5 and 11, C L = 15pF, S1 closed,B - A = 2Vt ZL(SHDN)Receiver Enable from Shutdownto Output Low (MAX481)ns 40100t ZL(SHDN)Driver Enable from Shutdown toOutput Low (MAX481)ns 3001000t ZH(SHDN)Receiver Enable from Shutdownto Output High (MAX481)UNITS MINTYP MAX SYMBOLPARAMETERt PLH t SKEW Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFt PHL Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFDriver Input to Output Driver Output Skew to Output ns 100800ns ns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S2 closedt ZH(SHDN)Driver Enable from Shutdown to Output High2502000ns2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S1 closedt ZL(SHDN)Receiver Enable from Shutdown to Output Lowns 2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S2 closedt ZH(SHDN)Receiver Enable from Shutdown to Output Highns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S1 closedt ZL(SHDN)Driver Enable from Shutdown to Output Lowns 50200600MAX483/MAX487 (Note 5) t SHDN Time to Shutdownt PHL t PLH , t PHL < 50% of data period Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 100pF, S2 closed CONDITIONSkbps 250f MAX 2508002000Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 25080020002050t LZ Receiver Disable Time from Low ns 2050t ZH Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low ns ns 1003003000t HZ t SKD Driver Disable Time from High I t PLH - t PHL I DifferentialReceiver SkewFigures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFns 3003000t LZ Driver Disable Time from Low ns 2502000t ZL Driver Enable to Output Low ns Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFns 2502000t R , t F 2502000Driver Rise or Fall Time ns t PLH Receiver Input to Output2502000t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________530002.5OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGE525M A X 481-01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )1.515100.51.02.0203540450.90.1-50-252575RECEIVER OUTPUT LOW VOLTAGE vs.TEMPERATURE0.30.7TEMPERATURE (°C)O U T P U TL O W V O L T A G E (V )500.50.80.20.60.40100125-20-41.5 2.0 3.0 5.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGE-8-16M A X 481-02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )2.5 4.0-12-18-6-14-10-203.54.5 4.83.2-50-252575RECEIVER OUTPUT HIGH VOLTAGE vs.TEMPERATURE3.64.4TEMPERATURE (°C)O U T P UT H I G H V O L T A G E (V )0504.04.63.44.23.83.01001259000 1.0 3.0 4.5DRIVER OUTPUT CURRENT vs.DIFFERENTIAL OUTPUT VOLTAGE1070M A X 481-05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )2.0 4.05030806040200.5 1.5 2.53.5 2.31.5-50-2525125DRIVER DIFFERENTIAL OUTPUT VOLTAGEvs. TEMPERATURE1.72.1TEMPERATURE (°C)D I F FE R E N T I A L O U T P U T V O L T A G E (V )751.92.21.62.01.8100502.4__________________________________________Typical Operating Characteristics(V CC = 5V, T A = +25°C, unless otherwise noted.)NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICSNote 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to deviceground unless otherwise specified.Note 2:All typical specifications are given for V CC = 5V and T A = +25°C.Note 3:Supply current specification is valid for loaded transmitters when DE = 0V.Note 4:Applies to peak current. See Typical Operating Characteristics.Note 5:The MAX481/MAX483/MAX487 are put into shutdown by bringing RE high and DE low. If the inputs are in this state for lessthan 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 6___________________________________________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 5V, T A = +25°C, unless otherwise noted.)120008OUTPUT CURRENT vs.DRIVER OUTPUT LOW VOLTAGE20100M A X 481-07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )6604024801012140-1200-7-5-15OUTPUT CURRENT vs.DRIVER OUTPUT HIGH VOLTAGE-20-80M A X 481-08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )-31-603-6-4-2024-100-40100-40-60-2040100120MAX1487SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20608050020060040000140100-50-2550100MAX481/MAX485/MAX490/MAX491SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125100-50-2550100MAX483/MAX487–MAX489SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________7______________________________________________________________Pin DescriptionFigure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating CircuitM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487__________Applications InformationThe MAX481/MAX483/MAX485/MAX487–MAX491 and MAX1487 are low-power transceivers for RS-485 and RS-422 communications. The MAX481, MAX485, MAX490,MAX491, and MAX1487 can transmit and receive at data rates up to 2.5Mbps, while the MAX483, MAX487,MAX488, and MAX489 are specified for data rates up to 250kbps. The MAX488–MAX491 are full-duplex trans-ceivers while the MAX481, MAX483, MAX485, MAX487,and MAX1487 are half-duplex. In addition, Driver Enable (DE) and Receiver Enable (RE) pins are included on the MAX481, MAX483, MAX485, MAX487, MAX489,MAX491, and MAX1487. When disabled, the driver and receiver outputs are high impedance.MAX487/MAX1487:128 Transceivers on the BusThe 48k Ω, 1/4-unit-load receiver input impedance of the MAX487 and MAX1487 allows up to 128 transceivers on a bus, compared to the 1-unit load (12k Ωinput impedance) of standard RS-485 drivers (32 trans-ceivers maximum). Any combination of MAX487/MAX1487 and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481/MAX483/MAX485 and MAX488–MAX491 have standard 12k ΩReceiver Input impedance.Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 8_______________________________________________________________________________________Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating CircuitFigure 3. MAX489/MAX491 Pin Configuration and Typical Operating CircuitMAX483/MAX487/MAX488/MAX489:Reduced EMI and ReflectionsThe MAX483 and MAX487–MAX489 are slew-rate limit-ed, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 12 shows the dri-ver output waveform and its Fourier analysis of a 150kHz signal transmitted by a MAX481, MAX485,MAX490, MAX491, or MAX1487. High-frequency har-monics with large amplitudes are evident. Figure 13shows the same information displayed for a MAX483,MAX487, MAX488, or MAX489 transmitting under the same conditions. Figure 13’s high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________9_________________________________________________________________Test CircuitsFigure 4. Driver DC Test Load Figure 5. Receiver Timing Test LoadFigure 6. Driver/Receiver Timing Test Circuit Figure 7. Driver Timing Test LoadM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 10_______________________________________________________Switching Waveforms_________________Function Tables (MAX481/MAX483/MAX485/MAX487/MAX1487)Figure 8. Driver Propagation DelaysFigure 9. Driver Enable and Disable Times (except MAX488 and MAX490)Figure 10. Receiver Propagation DelaysFigure 11. Receiver Enable and Disable Times (except MAX488and MAX490)Table 1. TransmittingTable 2. ReceivingLow-Power Shutdown Mode (MAX481/MAX483/MAX487)A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled.In shutdown, the devices typically draw only 0.1µA of supply current.RE and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown.For the MAX481, MAX483, and MAX487, the t ZH and t ZL enable times assume the part was not in the low-power shutdown state (the MAX485/MAX488–MAX491and MAX1487 can not be shut down). The t ZH(SHDN)and t ZL(SHDN)enable times assume the parts were shut down (see Electrical Characteristics ).It takes the drivers and receivers longer to become enabled from the low-power shutdown state (t ZH(SHDN ), t ZL(SHDN)) than from the operating mode (t ZH , t ZL ). (The parts are in operating mode if the –R —E –,DE inputs equal a logical 0,1 or 1,1 or 0, 0.)Driver Output ProtectionExcessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short cir-cuits over the whole common-mode voltage range (see Typical Operating Characteristics ). In addition, a ther-mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.Propagation DelayMany digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 15–18 using Figure 14’s test circuit.The difference in receiver delay times, | t PLH - t PHL |, is typically under 13ns for the MAX481, MAX485,MAX490, MAX491, and MAX1487 and is typically less than 100ns for the MAX483 and MAX487–MAX489.The driver skew times are typically 5ns (10ns max) for the MAX481, MAX485, MAX490, MAX491, and MAX1487, and are typically 100ns (800ns max) for the MAX483 and MAX487–MAX489.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________1110dB/div0Hz5MHz500kHz/div10dB/div0Hz5MHz500kHz/divFigure 12. Driver Output Waveform and FFT Plot of MAX481/MAX485/MAX490/MAX491/MAX1487 Transmitting a 150kHz SignalFigure 13. Driver Output Waveform and FFT Plot of MAX483/MAX487–MAX489 Transmitting a 150kHz SignalM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 12______________________________________________________________________________________V CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CFigure 14. Receiver Propagation Delay Test CircuitFigure 15. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PHLFigure 16. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PLHPHL Figure 18. MAX483, MAX487–MAX489 Receiver t PLHLine Length vs. Data RateThe RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23.Figures 19 and 20 show the system differential voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 120Ωloads.Typical ApplicationsThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.Figures 21 and 22 show typical network applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23.To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possi-ble. The slew-rate-limited MAX483 and MAX487–MAX489are more tolerant of imperfect termination.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________13DIV Y -V ZRO5V 0V1V0V -1V5V 0V2µs/divFigure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable Figure 20. MAX483, MAX487–MAX489 System Differential Voltage at 110kHz Driving 4000ft of CableFigure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 NetworkM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 14______________________________________________________________________________________Figure 22. MAX488–MAX491 Full-Duplex RS-485 NetworkFigure 23. Line Repeater for MAX488–MAX491Isolated RS-485For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________15_______________Ordering Information_________________Chip TopographiesMAX481/MAX483/MAX485/MAX487/MAX1487N.C. RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND B N.C.V CCARE * Contact factory for dice specifications.__Ordering Information (continued)M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 16______________________________________________________________________________________TRANSISTOR COUNT: 248SUBSTRATE CONNECTED TO GNDMAX488/MAX490B RO 0.054"(1.372mm)0.080"(2.032mm)N.C. DIGND Z A V CCYN.C._____________________________________________Chip Topographies (continued)MAX489/MAX491B RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND Z A V CCYREMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________17Package Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)S O I C N .E P SM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 18______________________________________________________________________________________Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)MAX481/MAX483/MAX485/MAX487–MAX491Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________19©2003 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487P D I P N .E PSPackage Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)。

MAX系列芯片大全

MAXIM/DALLAS 中文数据资料DS12CR887, DS12R885, DS12R887 RTC，带有恒压涓流充电器DS1870 LDMOS RF功放偏置控制器DS1921L-F5X Thermochron iButtonDS1923 温度/湿度记录仪iButton，具有8kB数据记录存储器DS1982, DS1982-F3, DS1982-F5 1k位只添加iButton?DS1990A 序列号iButtonDS1990R, DS1990R-F3, DS1990R-F5 序列号iButtonDS1991 多密钥iButtonDS2129 LVD SCSI 27线调节器DS2401 硅序列号DS2406 双通道、可编址开关与1k位存储器DS2408 1-Wire、8通道、可编址开关DS2411 硅序列号，带有VCC输入DS2413 1-Wire双通道、可编址开关DS2430A 256位1-Wire EEPROMDS2431 1024位、1-Wire EEPROMDS2480B 串行、1-Wire线驱动器，带有负荷检测DS2482-100 单通道1-Wire主控制器DS2482-100 勘误表PDF: 2482-100A2DS2482-800, DS2482S-800 八通道1-Wire主控制器DS2482-800 勘误表PDF: 2482-800A2DS2502 1k位只添加存储器DS2505 16k位只添加存储器DS28E04-100 4096位、可寻址、1-Wire EEPROM，带有PIODS3170DK DS3/E3单芯片收发器开发板DS3231, DS3231S 高精度、I2C集成RTC/TCXO/晶振DS33Z44 四路以太网映射器DS3902 双路、非易失、可变电阻器，带有用户EEPROMDS3906 三路、非易失、小步长调节可变电阻与存储器DS3984 4路冷阴极荧光灯控制器DS4302 2线、5位DAC，提供三路数字输出DS80C400-KIT DS80C400评估套件DS80C410, DS80C411 具有以太网和CAN接口的网络微控制器DS80C410 勘误表PDF: 80C410A1DS89C430, DS89C440, DS89C450 超高速闪存微控制器DS89C430 勘误表PDF: 89C430A2DS89C440 勘误表PDF: 89C440A2DS89C450 勘误表PDF: 89C450A2DS89C430 勘误表PDF: 89C430A3DS89C440 勘误表PDF: 89C440A3DS89C450 勘误表PDF: 89C450A3DS89C430 勘误表PDF: 89C430A5DS89C440 勘误表PDF: 89C440A5DS89C450 勘误表PDF: 89C450A5DS9090K 1-Wire器件评估板, B版DS9097U-009, DS9097U-E25, DS9097U-S09 通用1-Wire COM端口适配器DS9490, DS9490B, DS9490R USB至1-Wire/iButton适配器MAX1034, MAX1035 8/4通道、±VREF多量程输入、串行14位ADCMAX1072, MAX1075 1.8Msps、单电源、低功耗、真差分、10位ADCMAX1076, MAX1078 1.8Msps、单电源供电、低功耗、真差分、10位ADC，内置电压基准MAX1146, MAX1147, MAX1148, MAX1149 多通道、真差分、串行、14位ADCMAX1149EVKIT MAX1149评估板/评估系统MAX1220, MAX1257, MAX1258 12位、多通道ADC/DAC，带有FIFO、温度传感器和GPIO端口MAX1224, MAX1225 1.5Msps、单电源、低功耗、真差分、12位ADCMAX1258EVKIT MAX1057, MAX1058, MAX1257, MAX1258评估板/评估系统MAX1274, MAX1275 1.8Msps、单电源、低功耗、真差分、12位ADCMAX13000E, MAX13001E, MAX13002E, MAX13003E, MAX13004E, MAX13005E 超低电压电平转换器MAX1302, MAX1303 8/4通道、±VREF多量程输入、串行16位ADCMAX1304, MAX1305, MAX1306, MAX1308, MAX1309, MAX1310, MAX1312, MAX1313,MAX1314 8/4/2通道、12位、同时采样ADC，提供±10V、±5V或0至+5V模拟输入范围MAX13050, MAX13052, MAX13053, MAX13054 工业标准高速CAN收发器，具有±80V故障保护MAX13080E, MAX13081E, MAX13082E, MAX13083E, MAX13084E, MAX13085E, MAX13086E, MAX13087E, MAX13088E, MAX13089E +5.0V、±15kV ESD保护、失效保护、热插拔、RS-485/RS-422收发器MAX13101E, MAX13102E, MAX13103E, MAX13108E 16通道、带有缓冲的CMOS逻辑电平转换器MAX1334, MAX1335 4.5Msps/4Msps、5V/3V、双通道、真差分10位ADCMAX1336, MAX1337 6.5Msps/5.5Msps、5V/3V、双通道、真差分8位ADCMAX13481E, MAX13482E, MAX13483E ±15kV ESD保护USB收发器, 外部/内部上拉电阻MAX1350, MAX1351, MAX1352, MAX1353, MAX1354, MAX1355, MAX1356, MAX1357 双路、高端、电流检测放大器和驱动放大器MAX1450 低成本、1%精确度信号调理器，用于压阻式传感器MAX1452 低成本、精密的传感器信号调理器MAX1487, MAX481, MAX483, MAX485, MAX487, MAX488, MAX489, MAX490, MAX491 低功耗、限摆率、RS-485/RS-422收发器MAX1492, MAX1494 3位半和4位半、单片ADC，带有LCD驱动器MAX1494EVKIT MAX1493, MAX1494, MAX1495评估板/评估系统MAX1497, MAX1499 3位半和4位半、单片ADC，带有LED驱动器和μC接口MAX1499EVKIT MAX1499评估板/评估系统MAX15000, MAX15001 电流模式PWM控制器, 可调节开关频率MAX1515 低电压、内置开关、降压/DDR调节器MAX1518B TFT-LCD DC-DC转换器, 带有运算放大器MAX1533, MAX1537 高效率、5路输出、主电源控制器，用于笔记本电脑MAX1533EVKIT MAX1533评估板MAX1540A, MAX1541 双路降压型控制器，带有电感饱和保护、动态输出和线性稳压器MAX1540EVKIT MAX1540评估板MAX1551, MAX1555 SOT23、双输入、USB/AC适配器、单节Li+电池充电器MAX1553, MAX1554 高效率、40V、升压变换器，用于2至10个白光LED驱动MAX1556, MAX1557 16μA IQ、1.2A PWM降压型DC-DC转换器MAX1556EVKIT MAX1556EVKIT评估板MAX1558, MAX1558H 双路、3mm x 3mm、1.2A/可编程电流USB开关，带有自动复位功能MAX1586A, MAX1586B, MAX1586C, MAX1587A, MAX1587C 高效率、低IQ、带有动态内核的PMIC，用于PDA和智能电话MAX16801A/B, MAX16802A/B 离线式、DC-DC PWM控制器, 用于高亮度LED驱动器MAX1858A, MAX1875A, MAX1876A 双路180°异相工作的降压控制器，具有排序/预偏置启动和POR MAX1870A 升/降压Li+电池充电器MAX1870AEVKIT MAX1870A评估板MAX1874 双路输入、USB/AC适配器、1节Li+充电器，带OVP与温度调节MAX1954A 低成本、电流模式PWM降压控制器，带有折返式限流MAX1954AEVKIT MAX1954A评估板MAX19700 7.5Msps、超低功耗模拟前端MAX19700EVKIT MAX19700评估板/评估系统MAX19705 10位、7.5Msps、超低功耗模拟前端MAX19706 10位、22Msps、超低功耗模拟前端MAX19707 10位、45Msps、超低功耗模拟前端MAX19708 10位、11Msps、超低功耗模拟前端MAX2041 高线性度、1700MHz至3000MHz上变频/下变频混频器，带有LO缓冲器/开关MAX2043 1700MHz至3000MHz高线性度、低LO泄漏、基站Rx/Tx混频器MAX220, MAX222, MAX223, MAX225, MAX230, MAX231, MAX232, MAX232A, MAX233,MAX233A, MAX234, MAX235, MAX236, MAX237, MAX238, MAX239, MAX240, MAX241,MAX242, MAX243, MAX244, MAX245, MAX246, MAX247, MAX248, MAX249 +5V供电、多通道RS-232驱动器/接收器MAX2335 450MHz CDMA/OFDM LNA/混频器MAX2370 完备的、450MHz正交发送器MAX2370EVKIT MAX2370评估板MAX2980 电力线通信模拟前端收发器MAX2986 集成电力线数字收发器MAX3013 +1.2V至+3.6V、0.1μA、100Mbps、8路电平转换器MAX3205E, MAX3207E, MAX3208E 双路、四路、六路高速差分ESD保护ICMAX3301E, MAX3302E USB On-the-Go收发器与电荷泵MAX3344E, MAX3345E ±15kV ESD保护、USB收发器，UCSP封装，带有USB检测MAX3394E, MAX3395E, MAX3396E ±15kV ESD保护、大电流驱动、双/四/八通道电平转换器, 带有加速电路MAX3535E, MXL1535E +3V至+5V、提供2500VRMS隔离的RS-485/RS-422收发器，带有±15kV ESD保护MAX3570, MAX3571, MAX3573 HI-IF单芯片宽带调谐器MAX3643EVKIT MAX3643评估板MAX3645 +2.97V至+5.5V、125Mbps至200Mbps限幅放大器，带有信号丢失检测器MAX3645EVKIT MAX3645评估板MAX3654 47MHz至870MHz模拟CATV互阻放大器MAX3654EVKIT MAX3654评估板MAX3657 155Mbps低噪声互阻放大器MAX3658 622Mbps、低噪声、高增益互阻前置放大器MAX3735, MAX3735A 2.7Gbps、低功耗、SFP激光驱动器MAX3737 多速率激光驱动器，带有消光比控制MAX3737EVKIT MAX3737评估板MAX3738 155Mbps至2.7Gbps SFF/SFP激光驱动器，带有消光比控制MAX3744, MAX3745 2.7Gbps SFP互阻放大器，带有RSSIMAX3744EVKIT, MAX3745EVKIT MAX3744, MAX3745评估板MAX3748, MAX3748A, MAX3748B 紧凑的、155Mbps至4.25Gbps限幅放大器MAX3785 6.25Gbps、1.8V PC板均衡器MAX3787EVKIT MAX3787评估板MAX3793 1Gbps至4.25Gbps多速率互阻放大器，具有光电流监视器MAX3793EVKIT MAX3793评估板MAX3805 10.7Gbps自适应接收均衡器MAX3805EVKIT MAX3805评估板MAX3840 +3.3V、2.7Gbps双路2 x 2交叉点开关MAX3841 12.5Gbps CML 2 x 2交叉点开关MAX3967 270Mbps SFP LED驱动器MAX3969 200Mbps SFP限幅放大器MAX3969EVKIT MAX3969评估板MAX3982 SFP铜缆预加重驱动器MAX3983 四路铜缆信号调理器MAX3983EVKIT MAX3983评估板MAX3983SMAEVKIT MAX3983 SMA连接器评估板MAX4079 完备的音频/视频后端方案MAX4079EVKIT MAX4079评估板MAX4210, MAX4211 高端功率、电流监视器MAX4210EEVKIT MAX4210E、MAX4210A/B/C/D/F评估板MAX4211EEVKIT MAX4211A/B/C/D/E/F评估板MAX4397 用于双SCART连接器的音频/视频开关MAX4397EVKIT MAX4397评估系统/评估板MAX4411EVKIT MAX4411评估板MAX4729, MAX4730 低电压、3.5、SPDT、CMOS模拟开关MAX4754, MAX4755, MAX4756 0.5、四路SPDT开关，UCSP/QFN封装MAX4758, MAX4759 四路DPDT音频/数据开关，UCSP/QFN封装MAX4760, MAX4761 宽带、四路DPDT开关MAX4766 0.075A至1.5A、可编程限流开关MAX4772, MAX4773 200mA/500mA可选的限流开关MAX4795, MAX4796, MAX4797, MAX4798 450mA/500mA限流开关MAX4826, MAX4827, MAX4828, MAX4829, MAX4830, MAX4831 50mA/100mA限流开关, 带有空载标记, μDFN封装MAX4832, MAX4833 100mA LDO，带有限流开关MAX4834, MAX4835 250mA LDO，带有限流开关MAX4836, MAX4837 500mA LDO，带有限流开关MAX4838A, MAX4840A, MAX4842A 过压保护控制器，带有状态指示FLAGMAX4850, MAX4850H, MAX4852, MAX4852H 双路SPDT模拟开关，可处理超摆幅信号MAX4851, MAX4851H, MAX4853, MAX4853H 3.5/7四路SPST模拟开关，可处理超摆幅信号MAX4854 7四路SPST模拟开关，可处理超摆幅信号MAX4854H, MAX4854HL 四路SPST、宽带、信号线保护开关MAX4855 0.75、双路SPDT音频开关，具有集成比较器MAX4864L, MAX4865L, MAX4866L, MAX4867, MAX4865, MAX4866 过压保护控制器，具有反向保护功能MAX4880 过压保护控制器, 内置断路开关MAX4881, MAX4882, MAX4883, MAX4884 过压保护控制器, 内部限流, TDFN封装MAX4901, MAX4902, MAX4903, MAX4904, MAX4905 低RON、双路SPST/单路SPDT、无杂音切换开关, 可处理负电压MAX4906, MAX4906F, MAX4907, MAX4907F 高速/全速USB 2.0开关MAX5033 500mA、76V、高效率、MAXPower降压型DC-DC变换器MAX5042, MAX5043 双路开关电源IC，集成了功率MOSFET和热插拔控制器MAX5058, MAX5059 可并联的副边同步整流驱动器和反馈发生器控制ICMAX5058EVKIT MAX5051, MAX5058评估板MAX5062, MAX5062A, MAX5063, MAX5063A, MAX5064, MAX5064A, MAX5064B 125V/2A、高速、半桥MOSFET驱动器MAX5065, MAX5067 双相、+0.6V至+3.3V输出可并联、平均电流模式控制器MAX5070, MAX5071 高性能、单端、电流模式PWM控制器MAX5072 2.2MHz、双输出、降压或升压型转换器，带有POR和电源失效输出MAX5072EVKIT MAX5072评估板MAX5074 内置MOSFET的电源IC，用于隔离型IEEE 802.3af PD和电信电源MAX5078 4A、20ns、MOSFET驱动器MAX5084, MAX5085 65V、200mA、低静态电流线性稳压器, TDFN封装MAX5088, MAX5089 2.2MHz、2A降压型转换器, 内置高边开关MAX5094A, MAX5094B, MAX5094C, MAX5094D, MAX5095A, MAX5095B, MAX5095C 高性能、单端、电流模式PWM控制器MAX5128 128抽头、非易失、线性变化数字电位器, 采用2mm x 2mm μDFN封装MAX5417, MAX5417L, MAX5417M, MAX5417N, MAX5417P, MAX5418, MAX5419 256抽头、非易失、I2C接口、数字电位器MAX5417LEVKIT MAX5417_, MAX5418_, MAX5419_评估板/评估系统MAX5477, MAX5478, MAX5479 双路、256抽头、非易失、I2C接口、数字电位器MAX5478EVKIT MAX5477/MAX5478/MAX5479评估板/评估系统MAX5490 100k精密匹配的电阻分压器，SOT23封装MAX5527, MAX5528, MAX5529 64抽头、一次性编程、线性调节数字电位器MAX5820 双路、8位、低功耗、2线、串行电压输出DACMAX5865 超低功耗、高动态性能、40Msps模拟前端MAX5920 -48V热插拔控制器，外置RsenseMAX5921, MAX5939 -48V热插拔控制器，外置Rsense、提供较高的栅极下拉电流MAX5932 正电源、高压、热插拔控制器MAX5932EVKIT MAX5932评估板MAX5936, MAX5937 -48V热插拔控制器，可避免VIN阶跃故障，无需RSENSEMAX5940A, MAX5940B IEEE 802.3af PD接口控制器，用于以太网供电MAX5940BEVKIT MAX5940B, MAX5940D评估板MAX5941A, MAX5941B 符合IEEE 802.3af标准的以太网供电接口/PWM控制器，适用于用电设备MAX5945 四路网络电源控制器，用于网络供电MAX5945EVKIT, MAX5945EVSYS MAX5945评估板/评估系统MAX5953A, MAX5953B, MAX5953C, MAX5953D IEEE 802.3af PD接口和PWM控制器，集成功率MOSFETMAX6640 2通道温度监视器，提供双路、自动PWM风扇速度控制器MAX6640EVKIT MAX6640评估系统/评估板MAX6641 兼容于SMBus的温度监视器，带有自动PWM风扇速度控制器MAX6643, MAX6644, MAX6645 自动PWM风扇速度控制器，带有过温报警输出MAX6678 2通道温度监视器，提供双路、自动PWM风扇速度控制器和5个GPIOMAX6695, MAX6696 双路远端/本地温度传感器，带有SMBus串行接口MAX6877EVKIT MAX6877评估板MAX6950, MAX6951 串行接口、+2.7V至+5.5V、5位或8位LED显示驱动器MAX6966, MAX6967 10端口、恒流LED驱动器和输入/输出扩展器，带有PWM亮度控制MAX6968 8端口、5.5V恒流LED驱动器MAX6969 16端口、5.5V恒流LED驱动器MAX6970 8端口、36V恒流LED驱动器MAX6977 8端口、5.5V恒流LED驱动器，带有LED故障检测MAX6978 8端口、5.5V恒流LED驱动器，带有LED故障检测和看门狗MAX6980 8端口、36V恒流LED驱动器, 带有LED故障检测和看门狗MAX6981 8端口、36V恒流LED驱动器, 带有LED故障检测MAX7030 低成本、315MHz、345MHz和433.92MHz ASK收发器, 带有N分频PLLMAX7032 低成本、基于晶振的可编程ASK/FSK收发器, 带有N分频PLLMAX7317 10端口、SPI接口输入/输出扩展器，带有过压和热插入保护MAX7319 I2C端口扩展器，具有8路输入，可屏蔽瞬态检测MAX7320 I2C端口扩展器, 带有八个推挽式输出MAX7321 I2C端口扩展器，具有8个漏极开路I/O口MAX7328, MAX7329 I2C端口扩展器, 带有八个I/O口MAX7347, MAX7348, MAX7349 2线接口、低EMI键盘开关和发声控制器MAX7349EVKIT MAX7349评估板/仿真: MAX7347/MAX7348MAX7375 3引脚硅振荡器MAX7381 3引脚硅振荡器MAX7389, MAX7390 微控制器时钟发生器, 带有看门狗MAX7391 快速切换时钟发生器, 带有电源失效检测MAX7445 4通道视频重建滤波器MAX7450, MAX7451, MAX7452 视频信号调理器，带有AGC和后肩钳位MAX7452EVKIT MAX7452评估板MAX7462, MAX7463 单通道视频重建滤波器和缓冲器MAX8505 3A、1MHz、1%精确度、内置开关的降压型调节器，带有电源就绪指示MAX8524, MAX8525 2至8相VRM 10/9.1 PWM控制器，提供精密的电流分配和快速电压定位MAX8525EVKIT MAX8523, MAX8525评估板MAX8533 更小、更可靠的12V、Infiniband兼容热插拔控制器MAX8533EVKIT MAX8533评估板MAX8545, MAX8546, MAX8548 低成本、宽输入范围、降压控制器，带有折返式限流MAX8550, MAX8551 集成DDR电源方案，适用于台式机、笔记本电脑及图形卡MAX8550EVKIT MAX8550, MAX8550A, MAX8551评估板MAX8552 高速、宽输入范围、单相MOSFET驱动器MAX8553, MAX8554 4.5V至28V输入、同步PWM降压控制器，适合DDR端接和负载点应用MAX8563, MAX8564 ±1%、超低输出电压、双路或三路线性n-FET控制器MAX8564EVKIT MAX8563, MAX8564评估板MAX8566 高效、10A、PWM降压调节器, 内置开关MAX8570, MAX8571, MAX8572, MAX8573, MAX8574, MAX8575 高效LCD升压电路，可True ShutdownMAX8571EVKIT MAX8570, MAX8571, MAX8572, MAX8573, MAX8574, MAX8575评估板MAX8576, MAX8577, MAX8578, MAX8579 3V至28V输入、低成本、迟滞同步降压控制器MAX8594, MAX8594A 5路输出PMIC，提供DC-DC核电源，用于低成本PDAMAX8594EVKIT MAX8594评估板MAX8632 集成DDR电源方案，适用于台式机、笔记本电脑和图形卡MAX8632EVKIT MAX8632评估板MAX8702, MAX8703 双相MOSFET驱动器，带有温度传感器MAX8707 多相、固定频率控制器，用于AMD Hammer CPU核电源MAX8716, MAX8717, MAX8757 交叉工作、高效、双电源控制器，用于笔记本电脑MAX8716EVKIT MAX8716评估板MAX8717EVKIT MAX8717评估板MAX8718, MAX8719 高压、低功耗线性稳压器，用于笔记本电脑MAX8725EVKIT MAX8725评估板MAX8727 TFT-LCD升压型、DC-DC变换器MAX8727EVKIT MAX8727评估板MAX8729 固定频率、半桥CCFL逆变控制器MAX8729EVKIT MAX8729评估板MAX8732A, MAX8733A, MAX8734A 高效率、四路输出、主电源控制器，用于笔记本电脑MAX8737 双路、低电压线性稳压器, 外置MOSFETMAX8737EVKIT MAX8737评估板MAX8738 EEPROM可编程TFT VCOM校准器, 带有I2C接口MAX8740 TFT-LCD升压型、DC-DC变换器MAX8743 双路、高效率、降压型控制器，关断状态下提供高阻MAX8751 固定频率、全桥、CCFL逆变控制器MAX8751EVKIT MAX8751评估板MAX8752 TFT-LCD升压型、DC-DC变换器MAX8758 具有开关控制和运算放大器的升压调节器, 用于TFT LCDMAX8758EVKIT MAX8758评估板MAX8759 低成本SMBus CCFL背光控制器MAX8760 双相、Quick-PWM控制器，用于AMD Mobile Turion 64 CPU核电源MAX8764 高速、降压型控制器，带有精确的限流控制，用于笔记本电脑MAX9223, MAX9224 22位、低功耗、5MHz至10MHz串行器与解串器芯片组MAX9225, MAX9226 10位、低功耗、10MHz至20MHz串行器与解串器芯片组MAX9483, MAX9484 双输出、多模CD-RW/DVD激光二极管驱动器MAX9485 可编程音频时钟发生器MAX9485EVKIT MAX9485评估板MAX9486 8kHz参考时钟合成器，提供35.328MHz倍频输出MAX9486EVKIT MAX9486评估板MAX9489 多路输出网络时钟发生器MAX9500, MAX9501 三通道HDTV滤波器MAX9500EVKIT MAX9500评估板MAX9501EVKIT MAX9501评估板MAX9502 2.5V视频放大器, 带有重建滤波器MAX9504A, MAX9504B 3V/5V、6dB视频放大器, 可提供大电流输出MAX9701 1.3W、无需滤波、立体声D类音频功率放大器MAX9701EVKIT MAX9701评估板MAX9702 1.8W、无需滤波、立体声D类音频功率放大器和DirectDrive立体声耳机放大器MAX9702EVSYS/EVKIT MAX9702/MAX9702B评估系统/评估板MAX9703, MAX9704 10W立体声/15W单声道、无需滤波的扩展频谱D类放大器MAX9705 2.3W、超低EMI、无需滤波、D类音频放大器MAX9705BEVKIT MAX9705B评估板MAX9710EVKIT MAX9710评估板MAX9712 500mW、低EMI、无需滤波、D类音频放大器MAX9713, MAX9714 6W、无需滤波、扩频单声道/立体声D类放大器MAX9714EVKIT MAX9704, MAX9714评估板MAX9715 2.8W、低EMI、立体声、无需滤波、D类音频放大器MAX9715EVKIT MAX9715评估板MAX9716, MAX9717 低成本、单声道、1.4W BTL音频功率放大器MAX9716EVKIT MAX9716评估板MAX9718, MAX9719 低成本、单声道/立体声、1.4W差分音频功率放大器MAX9718AEVKIT MAX9718A评估板MAX9719AEVKIT MAX9719A/B/C/D评估板MAX9721 1V、固定增益、DirectDrive、立体声耳机放大器，带有关断MAX9721EVKIT MAX9721评估板MAX9722A, MAX9722B 5V、差分输入、DirectDrive、130mW立体声耳机放大器，带有关断MAX9722AEVKIT MAX9722A, MAX9722B评估板MAX9723 立体声DirectDrive耳机放大器, 具有BassMax、音量控制和I2C接口MAX9725 1V、低功率、DirectDrive、立体声耳机放大器，带有关断MAX9728AEVKIT MAX9728A/MAX9728B评估板MAX9750, MAX9751, MAX9755 2.6W立体声音频功放和DirectDrive耳机放大器MAX9759 3.2W、高效、低EMI、无需滤波、D类音频放大器MAX9759EVKIT MAX9759评估板MAX9770, MAX9772 1.2W、低EMI、无需虑波、单声道D类放大器，带有立体声DirectDrive耳机放大器MAX9787 2.2W立体声音频功率放大器, 提供模拟音量控制MAX9850 立体声音频DAC，带有DirectDrive耳机放大器MAX9890 音频咔嗒声-怦然声抑制器MAX9951, MAX9952 双路引脚参数测量单元MAX9960 双闪存引脚电子测量/高压开关矩阵MAX9961, MAX9962 双通道、低功耗、500Mbps ATE驱动器/比较器，带有2mA负载MAX9967 双通道、低功耗、500Mbps ATE驱动器/比较器，带有35mA负载MAX9986A SiGe高线性度、815MHz至1000MHz下变频混频器, 带有LO缓冲器/开关MAXQ2000 低功耗LCD微控制器MAXQ2000 勘误表PDF: MAXQ2000A2MAXQ2000-KIT MAXQ2000评估板MAXQ3120-KIT MAXQ3120评估板MXL1543B +5V、多协议、3Tx/3Rx、软件可选的时钟/数据收发器。

rs485通讯节点数

１　关于节点数：　所谓节点数、即每个ＲＳ－４８５接口芯片的驱动器能驱动多少个标准ＲＳ－４８５负载、根据规定、标准ＲＳ－４８５接口的输入阻抗为≥１２ｋΩ、相应的标准驱动节点数为３２、为适应更多节点的通信场合、有些芯片的输入阻抗设计成１／２负载（≥２４ｋΩ）、１／４负载（≥４８ｋΩ）甚至１／８负载（≥９６ｋΩ）、相应的节点数可增加到６４、１２８和２５６、　下列为常用的一些驱动ＩＣ比较：　型　号　３２个节点：　ＳＮ７５１７６、ＳＮ７５２７６、ＳＮ７５１７９、ＳＮ７５１８０、ＭＡＸ４８５、ＭＡＸ４８８、ＭＡＸ４９０　６４个节点：　ＳＮ７５ＬＢＣ１８４　１２８个节点：　ＭＡＸ４８７、ＭＡＸ１４８７　２５６个节点：　ＭＡＸ１４８２、ＭＡＸ１４８３、ＭＡＸ３０８０～ＭＡＸ３０８９　２　半双工和全双工芯片介绍　ＲＳ－４８５接口可连接成半双工和全双工两种通信方式、半双工通信的芯片有ＳＮ７５１７６、ＳＮ７５２７６、ＳＮ７５ＬＢＣ１８４、ＭＡＸ４８５、ＭＡＸ　１４８７、ＭＡＸ３０８２、ＭＡＸ１４８３等、全双工通信的芯片有ＳＮ７５１７９、ＳＮ７５１８０、ＭＡＸ４８８￣ＭＡＸ４９１、ＭＡＸ１４８２等、　３　应用中的常见问题　抗雷击和抗静电冲击：　ＲＳ－４８５接口芯片在使用、焊接或设备的运输途中都有可能受到静电的冲击而损坏、在传输线架设于户外的使用场合、接口芯片乃至整个系统还有可能遭致雷电的袭击、选用抗静电或抗雷击的芯片可有效避免此类损失、常见的芯片有ＭＡＸ４８５Ｅ、ＭＡＸ４８７Ｅ、ＭＡＸ１４８７Ｅ等、特别值得一提的是ＳＮ７５ＬＢＣ１８４、它不但能抗雷电的冲击而且能承受高达８ｋＶ的静电放电冲击、是目前市场上不可多得的一款产品、　限斜率驱动：　由于信号在传输过程中会产生电磁干扰和终端反射、使有效信号和无效信号在传输线上相互迭加、严重时会使通信无法正常进行、为解决这一问题、某些芯片的驱动器设计成限斜率方式、使输出信号边沿不要过陡、以不致于在传输线上产生过多的高频分量、从而有效地扼制干扰的产生、如ＭＡＸ４８７、ＳＮ７５ＬＢＣ１８４等都具有此功能、故障薄：　ⅳ故障薄技术是近两年产生的、一些新的ＲＳ－４８５芯片都采ⅳ用了此项技术、如ＳＮ７５２７６、ＭＡＸ３０８０￣ＭＡＸ３０８９、什么是故障薄、为什么要有故障薄、如果没有故障薄会产生什么ⅳⅳⅳ后果？　众所周知、ＲＳ－４８５接口采用的是一种差分传输方式、各节点之间的通信都是通过一对（半双工）或两对（全双工）双绞线作为传输介质、根据ＲＳ－４８５的标准规定、接收器的接收灵敏度为±２００ｍＶ、即接收端的差分电压大于、等于＋２００　ｍＶ时、接收器输出为高电平、小于、等于－２００ｍＶ时、接收器输出为低电平、介于±２００ｍＶ之间时、接收器输出为不确定状态、在总线空闲即传输线上所有节点都为接收状态以及在传输线开路或短路故障时、若不采取特殊措施、则接收器可能输出高电平也可能输出低电平、一旦某个节点的接收器产生低电平就会使串行接收器（ＵＡＲＴ）找不到起始位、从而引起通信异常、解决此类问题的方法有两种：　用带故障薄的芯片、它会在总线开路、短路和空（１）使ⅳ闲情况下、使接收器的输出为高电平、确保总线空闲、短路时接收器输出高电平是由改变接收器输入门限来实现的、例如、ＭＡＸ３０８０～ＭＡＸ　３０８９输入灵敏度为－５０ｍＶ／－２００ｍＶ、即差分接收器输入电压ＵＡ－Ｂ≥－５０ｍＶ时、接收器输出逻辑高电平、如果ＵＡ－Ｂ≤－２００ｍＶ、则输出逻辑低电平、当接收器输入端总线短路或总线上所有发送器被禁止时、接收器差分输入端为０Ｖ、从而使接收器输出高电平、同理、ＳＮ７５２７６的灵、因而达到故障薄的目的、　敏度为０ｍＶ／－３００ｍＶⅳ）若使用不带故障薄的芯片、如ＳＮ７５１７６、ＭＡＸ１４８７等（２ⅳ时、可在软件上作一些处理、从而避免通信异常、即在进入正常的数据通信之前、由主机预先将总线驱动为大于＋２００ｍＶ、并保持一段时间、使所有节点的接收器产生高电平输出、这样、在发出有效数据时、所有接收器能够正确地接收到起始位、进而接收到完整的数据、５　光电隔离　在某些工业控制领域、由于现场情况十分复杂、各个节点之间存在很高的共模电压、虽然ＲＳ－４８５接口采用的是差分传输方式、具有一定的抗共模干扰的能力、但当共模电压超过ＲＳ－４８５接收器的极限接收电压、即大于＋１２Ｖ或小于－７Ｖ时、接收器就再也无法正常工作了、严重时甚至会烧毁芯片和仪器设备、　解决此类问题的方法是通过ＤＣ－ＤＣ将系统电源和ＲＳ－４８５收发器的电源隔离、通过光耦将信号隔离、彻底消除共模电压的影响、实现此方案的途径可分为：　（１）用光耦、带隔离的ＤＣ－ＤＣ、ＲＳ－４８５芯片构筑电路、　（２）使用二次集成芯片、如ＰＳ１４８０、ＭＡＸ１４８０等、　以上主要介绍在不同场合如何选择合适的ＲＳ－４８５接口芯片、和可能碰到的有关问题的解决方法、从而避免通信异常、至于其它诸如终端匹配、传输线的选择和屏蔽、通信速率的选择等等、在一些相关资料中都能找到答案、这里就不再介绍了、　。

常见的USB、232、485、422的转换电缆制作方法

RS232转RS485232转485的芯片有MAX485,MAX489,MAX490,MAX491,MAX3082、MAX3221、MAX3491等RS485: 逻辑1：+（2—6）V表示；逻辑0：—（2—6）V表示RS232:逻辑"1"为-3 到-15V；逻辑"0"为+3 到+15V制作方法1：RS232-485转换器主要包括了电源、232电平转换、485电路三部分。

电路的供电直接从PC机的RS232接口中的DTR（4脚）和RTS（7脚）窃取。

PC串口每根线可以提供大约9mA的电流，因此两根线提供的电流足够供给这个电路使用了。

经实验，本电路只使用其中一条线也能够正常工作。

使用本电路需注意PC程序必须使串口的DTR和RTS输出高电平，经过D3稳压后得到VCC，经过实际测试，VCC电压大约在4.7V左右。

本电路的232电平转换电路采用了HIN232或者也可以直接使用MAX232集成电路，485电路采用了MAX485集成电路。

MAX485是通过两个引脚RE（2脚）和DE（3脚）来控制数据的输入和输出。

当RE为低电平时，MAX485数据输入有效；当DE为高电平时，MAX485数据输出有效。

在半双工使用中，通常可以将这两个脚直接相连，然后由PC或者单片机输出的高低电平就可以让MAX485在接收和发送状态之间转换了。

由于本电路DTR和RTS都用于了电路供电，因此使用TX线和HIN232的另外一个通道及Q1来控制MAX485的状态切换。

平时HIN232的9脚输出高电平，经Q1倒相后，使MAX485的RE和DE为低电平而处于数据接收状态。

当PC机发送数据时，HIN232的9脚输出低电平，经Q1倒相后，使MAX485的RE和DE为高电平而处于数据发送状态。

二，根据PC232与西门子plc的PPI口485的连接方式：3－Data＋8－Data－，可制作：制作2：注：681是阻值为680欧的电阻；682是阻值是6.8K的电阻。

MAX490_1281949

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .General DescriptionThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. The MAX483, MAX487, MAX488, and MAX489feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables,thus allowing error-free data transmission up to 250kbps.The driver slew rates of the MAX481, MAX485, MAX490,MAX491, and MAX1487 are not limited, allowing them to transmit up to 2.5Mbps.These transceivers draw between 120µA and 500µA of supply current when unloaded or fully loaded with disabled drivers. Additionally, the MAX481, MAX483, and MAX487have a low-current shutdown mode in which they consume only 0.1µA. All parts operate from a single 5V supply.Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-imped-ance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.The MAX487 and MAX1487 feature quarter-unit-load receiver input impedance, allowing up to 128 MAX487/MAX1487 transceivers on the bus. Full-duplex communi-cations are obtained using the MAX488–MAX491, while the MAX481, MAX483, MAX485, MAX487, and MAX1487are designed for half-duplex applications.________________________ApplicationsLow-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks__Next Generation Device Features♦For Fault-Tolerant ApplicationsMAX3430: ±80V Fault-Protected, Fail-Safe, 1/4Unit Load, +3.3V, RS-485 TransceiverMAX3440E–MAX3444E: ±15kV ESD-Protected,±60V Fault-Protected, 10Mbps, Fail-Safe, RS-485/J1708 Transceivers♦For Space-Constrained ApplicationsMAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,Profibus RS-485/RS-422 TransceiversMAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 PackageMAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422,True Fail-Safe ReceiversMAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,SOT23, RS-855/RS-422 Transmitters ♦For Multiple Transceiver ApplicationsMAX3030E–MAX3033E: ±15kV ESD-Protected,+3.3V, Quad RS-422 Transmitters ♦For Fail-Safe ApplicationsMAX3080–MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited RS-485/RS-422Transceivers♦For Low-Voltage ApplicationsMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited,True RS-485/RS-422 TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________Selection Table19-0122; Rev 8; 10/03Ordering Information appears at end of data sheet.查询MAX490供应商M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 2_______________________________________________________________________________________ABSOLUTE MAXIMUM RATINGSSupply Voltage (V CC ).............................................................12V Control Input Voltage (RE , DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (A, B)...................................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO).....................-0.5V to (V CC +0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW 8-Pin µMAX (derate 4.1mW/°C above +70°C)..............830mW 8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW 14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW Operating Temperature RangesMAX4_ _C_ _/MAX1487C_ A...............................0°C to +70°C MAX4__E_ _/MAX1487E_ A.............................-40°C to +85°C MAX4__MJ_/MAX1487MJA...........................-55°C to +125°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CDC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.V V IN = -7VV IN = 12V V IN = -7V V IN = 12V Input Current (A, B)I IN2V TH k Ω48-7V ≤V CM ≤12V, MAX487/MAX1487R INReceiver Input Resistance -7V ≤V CM ≤12V, all devices except MAX487/MAX1487R = 27Ω(RS-485), Figure 40.4V ≤V O ≤2.4VR = 50Ω(RS-422)I O = 4mA, V ID = -200mV I O = -4mA, V ID = 200mV V CM = 0V-7V ≤V CM ≤12V DE, DI, RE DE, DI, RE MAX487/MAX1487,DE = 0V, V CC = 0V or 5.25VDE, DI, RE R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4DE = 0V;V CC = 0V or 5.25V,all devices except MAX487/MAX1487CONDITIONSk Ω12µA ±1I OZRThree-State (high impedance)Output Current at ReceiverV 0.4V OL Receiver Output Low Voltage 3.5V OH Receiver Output High Voltage mV 70∆V TH Receiver Input Hysteresis V -0.20.2Receiver Differential Threshold Voltage-0.2mA 0.25mA-0.81.01.55V OD2Differential Driver Output (with load)V 2V 5V OD1Differential Driver Output (no load)µA±2I IN1Input CurrentV 0.8V IL Input Low Voltage V 2.0V IH Input High Voltage V 0.2∆V OD Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States V 0.2∆V OD Change in Magnitude of Driver Differential Output Voltage for Complementary Output States V 3V OC Driver Common-Mode Output VoltageUNITS MINTYPMAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________3SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)DC ELECTRICAL CHARACTERISTICS (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)ns 103060t PHLDriver Rise or Fall Time Figures 6 and 8, R DIFF = 54Ω, C L1= C L2= 100pF ns MAX490M, MAX491M MAX490C/E, MAX491C/E2090150MAX481, MAX485, MAX1487MAX490M, MAX491MMAX490C/E, MAX491C/E MAX481, MAX485, MAX1487Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pF MAX481 (Note 5)Figures 5 and 11, C RL = 15pF, S2 closedFigures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 6 and 8,R DIFF = 54Ω,C L1= C L2= 100pF Figures 6 and 10,R DIFF = 54Ω,C L1= C L2= 100pF CONDITIONS ns 510t SKEW ns50200600t SHDNTime to ShutdownMbps 2.5f MAX Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 103060t PLH 2050t LZ Receiver Disable Time from Low ns 2050t ZH Driver Input to Output Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low 2090200ns ns 134070t HZ t SKD Driver Disable Time from High |t PLH - t PHL |DifferentialReceiver Skewns 4070t LZ Driver Disable Time from Low ns 4070t ZL Driver Enable to Output Low 31540ns51525ns 31540t R , t F 2090200Driver Output Skew to Output t PLH , t PHL Receiver Input to Output4070t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERFigures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closedM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 4_______________________________________________________________________________________SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)3001000Figures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 5 and 11, C L = 15pF, S2 closed,A - B = 2VCONDITIONSns 40100t ZH(SHDN)Driver Enable from Shutdown toOutput High (MAX481)nsFigures 5 and 11, C L = 15pF, S1 closed,B - A = 2Vt ZL(SHDN)Receiver Enable from Shutdownto Output Low (MAX481)ns 40100t ZL(SHDN)Driver Enable from Shutdown toOutput Low (MAX481)ns 3001000t ZH(SHDN)Receiver Enable from Shutdownto Output High (MAX481)UNITS MINTYP MAX SYMBOLPARAMETERt PLH t SKEW Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFt PHL Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFDriver Input to Output Driver Output Skew to Output ns 100800ns ns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S2 closedt ZH(SHDN)Driver Enable from Shutdown to Output High2502000ns2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S1 closedt ZL(SHDN)Receiver Enable from Shutdown to Output Lowns 2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S2 closedt ZH(SHDN)Receiver Enable from Shutdown to Output Highns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S1 closedt ZL(SHDN)Driver Enable from Shutdown to Output Lowns 50200600MAX483/MAX487 (Note 5) t SHDN Time to Shutdownt PHL t PLH , t PHL < 50% of data period Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 100pF, S2 closed CONDITIONSkbps 250f MAX 2508002000Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 25080020002050t LZ Receiver Disable Time from Low ns 2050t ZH Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low ns ns 1003003000t HZ t SKD Driver Disable Time from High I t PLH - t PHL I DifferentialReceiver SkewFigures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFns 3003000t LZ Driver Disable Time from Low ns 2502000t ZL Driver Enable to Output Low ns Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFns 2502000t R , t F 2502000Driver Rise or Fall Time ns t PLH Receiver Input to Output2502000t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________530002.5OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGE525M A X 481-01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )1.515100.51.02.0203540450.90.1-50-252575RECEIVER OUTPUT LOW VOLTAGE vs.TEMPERATURE0.30.7TEMPERATURE (°C)O U T P UT L O W V O L T A G E (V )500.50.80.20.60.40100125-20-41.5 2.0 3.0 5.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGE-8-16M A X 481-02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )2.5 4.0-12-18-6-14-10-203.54.5 4.83.2-50-252575RECEIVER OUTPUT HIGH VOLTAGE vs.TEMPERATURE3.64.4TEMPERATURE (°C)O U T P UT H I G H V O L T A G E (V )0504.04.63.44.23.83.01001259000 1.0 3.0 4.5DRIVER OUTPUT CURRENT vs.DIFFERENTIAL OUTPUT VOLTAGE1070M A X 481-05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )2.0 4.05030806040200.5 1.5 2.53.5 2.31.5-50-2525125DRIVER DIFFERENTIAL OUTPUT VOLTAGEvs. TEMPERATURE1.72.1TEMPERATURE (°C)D I F FE R E N T I A L O U T P U T V O L T A G E (V )751.92.21.62.01.8100502.4__________________________________________Typical Operating Characteristics(V CC = 5V, T A = +25°C, unless otherwise noted.)NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICSNote 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to deviceground unless otherwise specified.Note 2:All typical specifications are given for V CC = 5V and T A = +25°C.Note 3:Supply current specification is valid for loaded transmitters when DE = 0V.Note 4:Applies to peak current. See Typical Operating Characteristics.Note 5:The MAX481/MAX483/MAX487 are put into shutdown by bringing RE high and DE low. If the inputs are in this state for lessthan 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 6___________________________________________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 5V, T A = +25°C, unless otherwise noted.)120008OUTPUT CURRENT vs.DRIVER OUTPUT LOW VOLTAGE20100M A X 481-07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )6604024801012140-1200-7-5-15OUTPUT CURRENT vs.DRIVER OUTPUT HIGH VOLTAGE-20-80M A X 481-08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )-31-603-6-4-2024-100-40100-40-60-2040100120MAX1487SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20608050020060040000140100-50-2550100MAX481/MAX485/MAX490/MAX491SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125100-50-2550100MAX483/MAX487–MAX489SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________7______________________________________________________________Pin DescriptionFigure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating CircuitM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487__________Applications InformationThe MAX481/MAX483/MAX485/MAX487–MAX491 and MAX1487 are low-power transceivers for RS-485 and RS-422 communications. The MAX481, MAX485, MAX490,MAX491, and MAX1487 can transmit and receive at data rates up to 2.5Mbps, while the MAX483, MAX487,MAX488, and MAX489 are specified for data rates up to 250kbps. The MAX488–MAX491 are full-duplex trans-ceivers while the MAX481, MAX483, MAX485, MAX487,and MAX1487 are half-duplex. In addition, Driver Enable (DE) and Receiver Enable (RE) pins are included on the MAX481, MAX483, MAX485, MAX487, MAX489,MAX491, and MAX1487. When disabled, the driver and receiver outputs are high impedance.MAX487/MAX1487:128 Transceivers on the BusThe 48k Ω, 1/4-unit-load receiver input impedance of the MAX487 and MAX1487 allows up to 128 transceivers on a bus, compared to the 1-unit load (12k Ωinput impedance) of standard RS-485 drivers (32 trans-ceivers maximum). Any combination of MAX487/MAX1487 and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481/MAX483/MAX485 and MAX488–MAX491 have standard 12k ΩReceiver Input impedance.Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 8_______________________________________________________________________________________Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating CircuitFigure 3. MAX489/MAX491 Pin Configuration and Typical Operating CircuitMAX483/MAX487/MAX488/MAX489:Reduced EMI and ReflectionsThe MAX483 and MAX487–MAX489 are slew-rate limit-ed, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 12 shows the dri-ver output waveform and its Fourier analysis of a 150kHz signal transmitted by a MAX481, MAX485,MAX490, MAX491, or MAX1487. High-frequency har-monics with large amplitudes are evident. Figure 13shows the same information displayed for a MAX483,MAX487, MAX488, or MAX489 transmitting under the same conditions. Figure 13’s high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________9_________________________________________________________________Test CircuitsFigure 4. Driver DC Test Load Figure 5. Receiver Timing Test LoadFigure 6. Driver/Receiver Timing Test Circuit Figure 7. Driver Timing Test LoadM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 10_______________________________________________________Switching Waveforms_________________Function Tables (MAX481/MAX483/MAX485/MAX487/MAX1487)Figure 8. Driver Propagation DelaysFigure 9. Driver Enable and Disable Times (except MAX488 and MAX490)Figure 10. Receiver Propagation DelaysFigure 11. Receiver Enable and Disable Times (except MAX488and MAX490)Table 1. TransmittingTable 2. ReceivingLow-Power Shutdown Mode (MAX481/MAX483/MAX487)A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled.In shutdown, the devices typically draw only 0.1µA of supply current.RE and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown.For the MAX481, MAX483, and MAX487, the t ZH and t ZL enable times assume the part was not in the low-power shutdown state (the MAX485/MAX488–MAX491and MAX1487 can not be shut down). The t ZH(SHDN)and t ZL(SHDN)enable times assume the parts were shut down (see Electrical Characteristics ).It takes the drivers and receivers longer to become enabled from the low-power shutdown state (t ZH(SHDN ), t ZL(SHDN)) than from the operating mode (t ZH , t ZL ). (The parts are in operating mode if the –R —E –,DE inputs equal a logical 0,1 or 1,1 or 0, 0.)Driver Output ProtectionExcessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short cir-cuits over the whole common-mode voltage range (see Typical Operating Characteristics ). In addition, a ther-mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.Propagation DelayMany digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 15–18 using Figure 14’s test circuit.The difference in receiver delay times, | t PLH - t PHL |, is typically under 13ns for the MAX481, MAX485,MAX490, MAX491, and MAX1487 and is typically less than 100ns for the MAX483 and MAX487–MAX489.The driver skew times are typically 5ns (10ns max) for the MAX481, MAX485, MAX490, MAX491, and MAX1487, and are typically 100ns (800ns max) for the MAX483 and MAX487–MAX489.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________1110dB/div0Hz5MHz500kHz/div10dB/div0Hz5MHz500kHz/divFigure 12. Driver Output Waveform and FFT Plot of MAX481/MAX485/MAX490/MAX491/MAX1487 Transmitting a 150kHz SignalFigure 13. Driver Output Waveform and FFT Plot of MAX483/MAX487–MAX489 Transmitting a 150kHz SignalM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 12______________________________________________________________________________________V CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CFigure 14. Receiver Propagation Delay Test CircuitFigure 15. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PHLFigure 16. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PLHPHL Figure 18. MAX483, MAX487–MAX489 Receiver t PLHLine Length vs. Data RateThe RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23.Figures 19 and 20 show the system differential voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 120Ωloads.Typical ApplicationsThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.Figures 21 and 22 show typical network applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23.To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possi-ble. The slew-rate-limited MAX483 and MAX487–MAX489are more tolerant of imperfect termination.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________13DIV Y -V ZRO5V 0V1V0V -1V5V 0V2µs/divFigure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable Figure 20. MAX483, MAX487–MAX489 System Differential Voltage at 110kHz Driving 4000ft of CableFigure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 NetworkM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 14______________________________________________________________________________________Figure 22. MAX488–MAX491 Full-Duplex RS-485 NetworkFigure 23. Line Repeater for MAX488–MAX491Isolated RS-485For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________15_______________Ordering Information_________________Chip TopographiesMAX481/MAX483/MAX485/MAX487/MAX1487N.C. RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND B N.C.V CCARE * Contact factory for dice specifications.__Ordering Information (continued)M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 16______________________________________________________________________________________TRANSISTOR COUNT: 248SUBSTRATE CONNECTED TO GNDMAX488/MAX490B RO 0.054"(1.372mm)0.080"(2.032mm)N.C. DIGND Z A V CCYN.C._____________________________________________Chip Topographies (continued)MAX489/MAX491B RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND Z A V CCYREMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________17Package Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)S O I C N .E P SM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 18______________________________________________________________________________________Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)MAX481/MAX483/MAX485/MAX487–MAX491Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________19©2003 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487P D I P N .E PSPackage Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)。

MAX485的功能

0 MAX485是芯片接口的一种类型。

MAX485接口芯片是Maxim公司的一种RS－485芯片。

MAX485CPAMAX485、MAX487-MAX491以及MAX1487是用于RS-485与RS-422通信的低功耗收发器，每个器件中都具有一个驱动器和一个接收器。

MAX483、MAX487、MAX488以及MAX489具有限摆率驱动器，可以减小EMI，并降低由不恰当的终端匹配电缆引起的反射，实现最高250kbps的无差错数据传输。

MAX481、MAX485、MAX490、MAX491、MAX1487的驱动器摆率不受限制，可以实现最高2.5Mbps 的传输速率。

这些收发器在驱动器禁用的空载或满载状态下，吸取的电源电流在120µA至500µA之间。

另外，MAX481、MAX483与MAX487具有低电流关断模式，仅消耗0.1µA。

所有器件都工作在5V单电源下。

采用单一电源+5 V工作，额定电流为300 μA，采用半双工通讯方式。

它完成将TTL电平转换为RS－485电平的功能。

MAX485芯片的结构和引脚都非常简单,内部含有一个驱动器和接收器。

RO 和DI端分别为接收器的输出和驱动器的输入端，与单片机连接时只需分别与单片机的RXD和TXD相连即可；/RE和DE端分别为接收和发送的使能端，当/RE为逻辑0时，器件处于接收状态；当DE为逻辑1时，器件处于发送状态，因为MAX485工作在半双工状态，所以只需用单片机的一个管脚控制这两个引脚即可；A端和B端分别为接收和发送的差分信号端,当A引脚的电平高于B 时，代表发送的数据为1；当A的电平低于B端时，代表发送的数据为0。

在与单片机连接时接线非常简单。

只需要一个信号控制MAX485的接收和发送即可。

同时将A和B端之间加匹配电阻，一般可选100Ω的电阻。

引脚(管脚)图及工作电路计算机是不能直接识别RS485通讯信号的。

单片机常用外围器件及芯片

常用MCS-51系列（8位）单片机内部硬件资源表更强功能的MCS-51系列（8位）单片机内部硬件资源表公司型号片内ROM 片内RAM I/O 口线中断源 A/D 定时器Intel80C51GA 4K 128 32 7 4*8bit 280C51GB 8K 256 32 7 4*8bit 2 ATMEL 89LV51 Flash 4K 128 32 6 /289LV52 Flash 8K 256 32 8 3 SiemensSAB80512 4K 128 56 6 8*8bit 2SAB80515 8K 256 48 12 8*8bit 3 AMD 80C525/325 8K 256 42 2 8*8bit380C515/535 8K 256 32 4 2Philips/ Signetics 83C552 8K 256 40 15 8*8bit 2 83C752 2K 64 19 6 4*8bit 1常用PIC 单片机系列（8位）单片机内部硬件资源型号管脚片内ROM(位) 片内RAM I/O口线说明PIC12C508A 8 512*12 256 每个I/O 口吸收、驱动电流25mAPIC12C509A 512*12 41PIC12C671 1024*12 128PIC12C671 2048*12 128每个I/O 口吸收、驱动电流25mA ，4路8位ADCPIC16C54C 18 512*12 25 12一个定时器，片内WDT ，每个I/O 口吸收25mA 电流、驱动电流20mAPIC16C55 28 512*12 24 20PIC16C56 18 1024*12 25 12PIC16C57 28 2048*12 72 20公司型号片内ROM片内RAM I/O 口线中断源定时/计数器 Intel8031/128 32 5 2 8751 4K EPROM 128 32 5 2 8051 4K 128 32 5 2 8752 8K EPROM 256 32 6 3 ATMEL 89C1051 1K FLASH 128 15 3 1 89C2051 2K FLASH 128 15 5 2 89C51 4K FLASH 128 32 5 2 89C52 8K FLASH2563283常用74系列门电路芯片型号和简单功能描述名称（74XX）特征描述00 四2输入端与非门01 四2输入端与非门（OC）02 四2输入端或非门03 四2输入端或非门（OC）04 六反相器05 六反相器（OC）06 六高压输出反相器（OC,30V）07 六高压输出缓冲驱动器（OC,30V）08 四2输入端与门10 三2输入端与非门11 三2输入端与门13 双4输入端与非门14 六反相器16 六高压输出反相器（OC,15V）17 六高压输出缓冲驱动器（OC,15V）128 四2输入端或非线驱动器常用4000系列门电路芯片型号和简单功能描述型号器件名称厂家名称CD4000 双3输入端或非门+单非门TICD4001 四2输入端或非门HIT/NSC/TI/GOL CD4002 双4输入端或非门NSCCD4011 四2输入端与非门HIT/TICD4012 双4输入端与非门NSCCD4023 三3输入端与非门NSC/MOT/TI CD4025 三3输入端或非门NSC/MOT/TI CD4068 八输入端与非门/与门NSC/HIT/TICD4069 六反相器NSC/HIT/TICD4073 三3输入端与门NSC /TICD4075 三3输入端或门NSC/ TICD4081 四2输入端与门NSC/HIT/TICD4082 双4输入端与门NSC/HIT/TI常用的功率MOSFET驱动器型号配置输出电流（A）最大输入电压（V）封装TC4421 单通道、反相9 18 8-Pin，PDIP,5-Pin TC429 单通道、反相 6 18 8-Pin PDIPTC1413 单通道、反相 3 16 8-Pin PDIP,8-Pin TC4427A 双通道 1.5 18 8-Pin PDIP,8-PinTC4428A 双通道、正反/相1.5 188-Pin PDIP,8-PinSOICTC1426 双通道、反相 1.2 16 8-Pin PDIP,8-Pin SOICTC4467 四通道、反相 1.2 18 14-Pin PDIP,16-Pin SOIC(W)TC4468 四通道 1.2 18 14-Pin PDIP,16-Pin SOIC(W)电流/电压转换芯片型号封装电流大小电源电压最大工作电流(µA）简单描述MAX471 8/PDIP/SO 0~3A +3~+36 50 精密，高端电流传感放大器MAX472 8/PDIP/SO 外部电阻+3~+36 20 精密，高端电流传感放大器MAX4073 5-SC706-SOT23外部电阻+3~+28 500低成本，电压输出高端电流传感放大器MAX4172 8/µMAX/SO 外部电阻+3~+32 800 低成本，精密，H输出高端电流传感放大器MAX4173 6-SOT23 外部电阻+3~+28 420 低成本，电压输出高端电流传感放大器MAX4372 5-SOT238-SO外部电阻+2.7~+28 30低成本，微功耗电压输出高端电流传感放大器+比较器，含电压基准MAX4373 8/µMAX/SO 外部电阻+2.7~+28 50 低成本，微功耗电压输出高端电流传感放大器+比较器，含电压基准MAX4374 8/µMAX/SO 外部电阻+2.7~+28 50 低成本，微功耗电压输出高端电流传感放大器+比较器，含电压基准MAX4375 8/µMAX/SO 外部电阻+2.7~+28 50 低成本，微功耗电压输出高端电流传感放大器+比较器，含电压基准MAX4376 14-TSSOP5-SOT238/µMAX/SO外部电阻+3~+28 1000单高变电流传感放大器带外部增益多路模拟开关型号仪表放大器型号传感器类型输出形式输出阻抗典型器件热敏电阻随温度电阻发生变化 50到1M Ω AD524、AD620 热电偶电压变化 20~20k Ω AD624、AD620电阻温度探测（RTD ）（桥式电路）随温度电阻发生变化 20~20k Ω AD624、AD625、AD620 水位传感器热型、浮标型电阻变化500~2k Ω100~2k Ω AD624、AD625、AD620、AMP-01负载传感器应变桥、测重仪电阻变化120~1k Ω AD624、AD625、AD620、 AMP-01 光敏二极管光强度增加，电流增加 10Ω AMP-05磁场传感器 5mv/kg ~120mv/kg 1~ 1k Ω AD624、AD625、AD620、 AMP-02加速度传感器 1~100mv/g500ΩAD624、AD625、AD620、 AMP-02AD 公司DAC 器件极性型号封装位数输出信号线性外部基准接口方式单极性AD5300BμSOIC8 0~+VDD 1 +VDD SPI AD7523 DIP 8 I 1/2 ±VREF P8 AD7524 DIP 8 I 1/2 ±VREF P8 AD7533 DIP10 I 1/2~2 ±VREF P10 AD5310BμSOIC10 0~+VDD 1 +VDD SPI AD7397 DIP 10 0~+VDD 1 +VREF P12 AD7541A DIP 12 I 1/2 ±VREF P12 AD7545 DIP 12 I 1/2 ±VREF P12 AD7845 DIP 12V1/2~1±VREFP12型号通道数最小电压最大电压最大关电流最大开时间最大关时间 MAX324 2 2.7 16 0.1 150 100 MAX323 2 2.7 16 0.1 150 100 MAX307 8 4.5 30 0.75 200 150 MAX306 16 4.5 30 0.75 200 150 MAX322 2 Dual-Supply Dual-Supply 0.1 150 100 MAX321 2 Dual-Supply Dual-Supply 0.1 150 100 MAX320 2Dual-Supply Dual-Supply 0.1 150100AD7564 DIP 12 I1/2 4路+VREF S AD7393 DIP 12 +1.2(V) 1.6 +1.2(内部) P10 AD7394 DIP 12 +VREF(V) 1 +VREF SPI AD5320B DIP 12 0~+VDD 1 +VDD SPI AD7538 μSOIC 14 I1 ±VREF P14AD420 DIP 16 I(0~20mA/ 0~24mA/ 4~24mA) / 内/外 SPI/Microwire AD421 DIP 16 I(4~24mA) / 内/外 SPI 双极性AD7225 DIP 8 V ±5（V ） I 5mA±2 4路外 P8 AD7226 DIP 8 V ±5（V ） I 5mA±2 1路外 P8 AD7243 DIP 12 V ±5（V ） I 5mA±1 +5 S AD7840 DIP14V ±3（V ） I 5mA±2+3P14TI 公司的双极性DAC 器件器件管脚数分辨率输出通道数基准电源电压 TLV5620 14 8 V 4 外部 2.7~5.5 TLC5628 16 8 V 8 外部 5TLV5604 16 10 V 8 外部 2.7~5.5 TLV5614 16 12 V 8 外部 2.7~5.5 TLC5615 8 10 V 1 外部 5TLC5616 8 12 V 1 外部 2.7~5.5 TLC5617 8 10 V 2 外部 5 TLC5618 8 12 V 2 外部 5TLV5636 8 12 V 1 外部 2.7~5.5 TLV5637 8 10 V 2 外部 2.7~5.5 TLV5638 8 12 V 2外部 2.7~5.5TLV5613 20 12 V 1 外部 2.7~5.5 TLV56192012 V1外部 2.7~5.5型号通道分辨率输出阻抗线性封装MAX5621 16 16 50 0.0015 64-TQFP 68-QFN MAX5622 16 16 500 0.0015 64-TQFP 68-QFN MAX5623 16 16 1000 0.0015 64-TQFP 68-QFN MAX5631 32 16 50 0.0015 64-TQFP 68-QFN MAX5632 32 16 500 0.0015 64-TQFP 68-QFN MAX5633 32 1610000.0015 64-TQFP 68-QFNTLV5633 20 12 V 1 内部 2.7~5.5 TLV5639 20 12 V 11 内部 2.7~5.5 THS5641 28 8 I 1 内部 3.0~5.0 THS5651 28 10 I 1 内部 3.0~5.0常用的光耦器件型号品牌描述4N25 QTC 晶体管输出4N30 QTC 达林顿管输出4N33 QTC 达林顿管输出4N35 QTC 晶体管输出6N135 FSC 高速光耦晶体管输出6N136 FSC 高速光耦晶体管输出6N137 FSC 高速光耦晶体管输出T1L113 FSC 达林顿管输出T1L117 - 达林顿管输出MOC3041 - 过零\触发\可控制输出MOC3061 - 过零\触发\可控制输出升/降压电压变换器件型号最小输出电压最大输出电压典型电流特征MAX1672 1.25 5.5 0.3 低电压检测MAX1729 2.5 16 0.0025 低噪声MAX710 - - 0.25 低噪声低电压检测MAX711 2.7 5.5 0.25 低噪声低电压检测升压电压变化器件型号最小输出电压最大输出电压典型电流MAX1675 2 5.5 0.3MAX1676 2 5.5 0.3MAX1678 2 5.5 0.09MAX1687 1.25 6 2MAX1688 1.25 6 2MAX1700 2.2 5.5 0.8MAX1703 2.5 5.5 1.5MAX1705 2.5 5.5 0.8降压电压变换器件型号典型输出值最小输出电压最大输出电压典型电流MAX1672 1.25 5.5 0.3 低电压检测MAX1734 1.5,1.8 - - 0.25MAX1742 1.5,1.8，2.5 1.1 5.5 1 MAX1744 3.3，5 - - 10 MAX1745 - 1.25 18 10 MAX1762 1.8,2.5 0.5 5.5 0.6 MAX1776 5 1.25 24 0.6 MAX1791 3.3,5 0.5 5.5 3 MAX1809 - 1.1 5.5 3 MAX1813 - 0.6 2 22 MAX1830 1.5,1.8,2.5 1.1 5.5 3低压差线性稳压器型号典型输出值最小输出电压最大输出电压典型电流（mA）MAX8873 2.80、2.84、3.15 - - 280MAX8874 2.80、2.84、3.15 - - 280MAX8875 2.5~5 - - 150MAX8877 2.5~5 - - 150MAX8878 2.5~5 - - 150MAX8880 - 1.25 5 200MAX8881 1.8、2.5、2.85、5.0 - - 200MAX8882 1.8、2.5、2.85、3.3 - - 160MAX8883 1.8、2.5、2.85、3.3 - - 160MAX8885 2.5~5 - - 150精密电压基准IC型号输出电压精度最小电压最大电压MAX6191A 2.048 0.1 2.5 12.6MAX6191B 2.048 0.244 2.5 12.6MAX6191C 2.048 0.5 2.5 12.6MAX6192A 2.5 0.08 2.7 12.6MAX6192B 2.5 0.2 2.7 12.6MAX6192C 2.5 0.4 2.7 12.6MAX6193A 3 0.066 3.2 12.6MAX6193B 3 0.166 3.2 12.6MAX6193C 3 0.333 3.2 12.6MAX6194A 4.5 0.04 4.7 12.6MAX6194B 4.5 0.11 4.7 12.6MAX6194C 4.5 0.22 4.7 12.6MAX6195A 5 0.04 5.2 12.6MAX6195B 5 0.1 5.2 12.6 MAX6195C 5 0.2 5.2 12.6 MAX6198A 4.096 0.05 4.3 12.6 MAX6198B 4.096 0.12 4.3 12.6 MAX6198C 4.096 0.24 4.3 12.6看门狗器件型号最小复位时间（ms）最大复位时间（ms）标准看门狗设置MAX690 35 70 可调1.6s MAX691 可调35 可调70 可调1.6s MAX692 可调35 可调70 可调1.6s MAX693 可调35 可调70 可调1.6s MAX694 可调140 可调280 可调1.6s MAX695 可调140 可调280 可调1.6s 单片机常用外围器件单片机常用外围器件************************************一、74系列常用器件1.常用与非门及与非门器件MM54HC08/MM74HC08MM54HC11/MM74HC12.常用或门有或非门器件MM54HC32/MM74HC32MM54HC02/MM74HC023常用与或门及与或非门器件MM54HC58/MM74HC58MM5(7)4HC514.常用总线驱动及收发器件54LS244/DM74LS244DM54LS235/DM74LS24574HC5955.常用计数器DM74LS90/DM74LS93DM54LS193/DM74LS1936.常用编码译码器件MM5(7)4HC148MM5(7)4HC138************************************二、存储器件1.SRAM-IS61C256AH2.EPRAM-M2764A3.EEPRAM24LC256X2816C4.FLASH存储器AT29C2***********************************三、A/D1.逐次比较型A/DADC0809/0804AD78102.并行比较型ADAD90483.半闪烁型高速A/DTLC5510MAX1134.Σ－△型高精度A/DAD7710ADS1100***********************************四、输出及显示1.LED驱动芯片ICM7218MAX7219MCI144892.LCD器件FYD128643.D/A************************************五、传感器1.温度LM35DS18B202.语音芯片ISD25003.时钟芯片DS1302PCF85834.其他热线型半导体气敏元件MR513酒精传感器 MQ-303A可燃性气体传感器 M007*************************************六、常用可编程器件1.可编程并行接口芯片 8255A2.可编程中断控制器 82C59A3.可编程计数器MSM82C53-2MSM82C54-24.可编程键盘、显示控制器件TMP82C79*****************************************七、常用通信器件1.RS-232总线接口芯片 MAX2322.RS-422总线接口芯片 MAX4913.RS-485总线接口芯片 MAX4854.异步收发器 MAX3100B控制器件 ISP15186.以太网接口器件 RTL8019AS*****************************************八、电源相关器件1.DC-DC电压变换器MAX1676MAX6822.电源监控器件MAX791MAX7053.电流传感器MAX471/472。

MAX491中文资料

Driver Input Voltage (DI).............................-0.5V to (VCC + 0.5V)
Driver Output Voltage (Y, Z; A, B) ..........................-8V to +12.5V
Receiver Input Voltage (A, B).................................-8V to +12.5V
For free samples & the latest literature: , or phone 1-800-998-8800
元器件交易网
MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E
______________Ordering Information
PART MAX481ECPA MAX481ECSA
TEMP. RANGE 0°C to +70°C 0°C to +70°C
PIN-PACKΒιβλιοθήκη GE 8 Plastic DIP 8 SO
________________________Applications
o ESD Protection: ±15kV—Human Body Model
o Slew-Rate Limited for Error-Free Data Transmission (MAX483E/487E/488E/489E)
o Low Quiescent Current: 120µA (MAX483E/487E/488E/489E) 230µA (MAX1487E) 300µA (MAX481E/485E/490E/491E)

MAX481_MAX483_MAX485_MAX487_MAX1487_MAX490_MAX491_中文资料

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_____________________________ _概述MAX481、MAX483、MAX485、MAX487-MAX491以及MAX1487是用于RS-485与RS-422通信的低功耗收发器，每个器件中都具有一个驱动器和一个接收器。

MAX483、MAX487、MAX488以及MAX489具有限摆率驱动器，可以减小EMI ，并降低由不恰当的终端匹配电缆引起的反射，实现最高250k b p s 的无差错数据传输。

M A X 481、MAX485、MAX490、MAX491、MAX1487的驱动器摆率不受限制，可以实现最高2.5Mbps 的传输速率。

这些收发器在驱动器禁用的空载或满载状态下，吸取的电源电流在120(A 至500(A 之间。

另外，MAX481、MAX483与MAX487具有低电流关断模式，仅消耗0.1µA 。

所有器件都工作在5V 单电源下。

驱动器具有短路电流限制，并可以通过热关断电路将驱动器输出置为高阻状态，防止过度的功率损耗。

接收器输入具有失效保护特性，当输入开路时，可以确保逻辑高电平输出。

MAX487与MAX1487具有四分之一单位负载的接收器输入阻抗，使得总线上最多可以有128个M A X 487/MAX1487收发器。

使用MAX488-MAX491可以实现全双工通信，而MAX481、MAX483、MAX485、MAX487与MAX1487则为半双工应用设计。

_______________________________应用低功耗RS-485收发器低功耗RS-422收发器电平转换器用于EMI 敏感应用的收发器工业控制局域网____________________下一代器件的特性♦容错应用MAX3430: ±80V 故障保护、失效保护、1/4单位负载、+3.3V 、RS-485收发器MAX3440E-MAX3444E: ±15kV ESD 保护、±60V 故障保护、10Mbps 、失效保护、RS-485/J1708收发器♦对于空间受限应用MAX3460-MAX3464: +5V 、失效保护、20Mbps 、Profibus RS-485/RS-422收发器MAX3362: +3.3V 、高速、RS-485/RS-422收发器，采用SOT23封装MAX3280E-MAX3284E: ±15kV ESD 保护、52Mbps 、+3V 至+5.5V 、SOT23、RS-485/RS-422、真失效保护接收器MAX3293/MAX3294/MAX3295: 20Mbps 、+3.3V 、SOT23、RS-485/RS-422发送器♦对于多通道收发器应用MAX3030E-MAX3033E: ±15kV ESD 保护、+3.3V 、四路RS-422发送器♦对于失效保护应用MAX3080-MAX3089: 失效保护、高速(10Mbps)、限摆率RS-485/RS-422收发器♦对于低电压应用MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V 供电、±15kV ESD 保护、12Mbps 、限摆率、真正的RS-485/RS-422收发器MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487低功耗、限摆率、RS-485/RS-422收发器_____________________________________________________________________选择表19-0122; Rev 8; 10/03定购信息在本资料的最后给出。

吊车梁设计

制动结构的作用：
承受横向水平力侧向支承上翼缘，保证吊车梁的整体稳定制动梁可兼作检修平台
制动桁架吊车梁
吊车梁
天窗架
山墙抗风柱
正在建设的门式刚架工程实例
单轴对称工字形截面(加强上翼缘）
适用范围：
Q≤ 30t，L≤ 6m， A1 ～ A5级
带制动梁的吊车梁
制动梁
吊车梁上翼缘制动板槽钢
2)横向水平荷载
用于挠度计算： Tk ( Q Q' )g / n 0.1( 50 15.4 ) 9.8 / 4 16.02kN 用于强度、稳定性和连接计算：
Tk 0.1Pk max 0.1 491 49.1kN T 1.4 0.1Pk max 1.4 0.1 491 68.74kN
中级桥式吊车：l/1000 重级桥式吊车：l/1200
注意：
《钢结构设计规范》（GB50017-2003）规定：对于工作级别为A7、A8吊车的制动结构，计算其水平挠度，按效应最大的一台吊车的荷载标准值计算，且不乘动力系数。
u M kymax l 2 l 10EI y1 2200
4、疲劳验算
何为吊车梁？主要承受吊车竖向及水平荷载，并将这些荷载传
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格构柱
吊车梁的类型
按支撑情况分
简支梁——应用最广。连续梁——经济，受柱的不均匀沉降影响明显，很少使用。
简支梁
连续梁
按结构体系分
实腹式型钢梁——适用于跨度6m，起重量≤10t的情况。焊接组合梁——应用较广
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确定翼缘板尺寸

MAX1487EPA+中文资料

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .General DescriptionThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. The MAX483, MAX487, MAX488, and MAX489feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables,thus allowing error-free data transmission up to 250kbps.The driver slew rates of the MAX481, MAX485, MAX490,MAX491, and MAX1487 are not limited, allowing them to transmit up to 2.5Mbps.These transceivers draw between 120µA and 500µA of supply current when unloaded or fully loaded with disabled drivers. Additionally, the MAX481, MAX483, and MAX487have a low-current shutdown mode in which they consume only 0.1µA. All parts operate from a single 5V supply.Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-imped-ance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.The MAX487 and MAX1487 feature quarter-unit-load receiver input impedance, allowing up to 128 MAX487/MAX1487 transceivers on the bus. Full-duplex communi-cations are obtained using the MAX488–MAX491, while the MAX481, MAX483, MAX485, MAX487, and MAX1487are designed for half-duplex applications.________________________ApplicationsLow-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks__Next Generation Device Features♦For Fault-Tolerant ApplicationsMAX3430: ±80V Fault-Protected, Fail-Safe, 1/4Unit Load, +3.3V, RS-485 TransceiverMAX3440E–MAX3444E: ±15kV ESD-Protected,±60V Fault-Protected, 10Mbps, Fail-Safe, RS-485/J1708 Transceivers♦For Space-Constrained ApplicationsMAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,Profibus RS-485/RS-422 TransceiversMAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 PackageMAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422,True Fail-Safe ReceiversMAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,SOT23, RS-855/RS-422 Transmitters ♦For Multiple Transceiver ApplicationsMAX3030E–MAX3033E: ±15kV ESD-Protected,+3.3V, Quad RS-422 Transmitters ♦For Fail-Safe ApplicationsMAX3080–MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited RS-485/RS-422Transceivers♦For Low-Voltage ApplicationsMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited,True RS-485/RS-422 TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________Selection Table19-0122; Rev 8; 10/03Ordering Information appears at end of data sheet.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 2_______________________________________________________________________________________ABSOLUTE MAXIMUM RATINGSSupply Voltage (V CC ).............................................................12V Control Input Voltage (RE , DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (A, B)...................................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO).....................-0.5V to (V CC +0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW 8-Pin µMAX (derate 4.1mW/°C above +70°C)..............830mW 8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW 14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW Operating Temperature RangesMAX4_ _C_ _/MAX1487C_ A...............................0°C to +70°C MAX4__E_ _/MAX1487E_ A.............................-40°C to +85°C MAX4__MJ_/MAX1487MJA...........................-55°C to +125°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CDC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.V V IN = -7VV IN = 12V V IN = -7V V IN = 12V Input Current (A, B)I IN2V TH k Ω48-7V ≤V CM ≤12V, MAX487/MAX1487R INReceiver Input Resistance -7V ≤V CM ≤12V, all devices except MAX487/MAX1487R = 27Ω(RS-485), Figure 40.4V ≤V O ≤2.4VR = 50Ω(RS-422)I O = 4mA, V ID = -200mV I O = -4mA, V ID = 200mV V CM = 0V-7V ≤V CM ≤12V DE, DI, RE DE, DI, RE MAX487/MAX1487,DE = 0V, V CC = 0V or 5.25VDE, DI, RE R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4R = 27Ωor 50Ω, Figure 4DE = 0V;V CC = 0V or 5.25V,all devices except MAX487/MAX1487CONDITIONSk Ω12µA ±1I OZRThree-State (high impedance)Output Current at ReceiverV 0.4V OL Receiver Output Low Voltage 3.5V OH Receiver Output High Voltage mV 70∆V TH Receiver Input Hysteresis V -0.20.2Receiver Differential Threshold Voltage-0.2mA 0.25mA-0.81.01.55V OD2Differential Driver Output (with load)V 2V 5V OD1Differential Driver Output (no load)µA±2I IN1Input CurrentV 0.8V IL Input Low Voltage V 2.0V IH Input High Voltage V 0.2∆V OD Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States V 0.2∆V OD Change in Magnitude of Driver Differential Output Voltage for Complementary Output States V 3V OC Driver Common-Mode Output VoltageUNITS MINTYPMAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________3SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)DC ELECTRICAL CHARACTERISTICS (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)ns 103060t PHLDriver Rise or Fall Time Figures 6 and 8, R DIFF = 54Ω, C L1= C L2= 100pF ns MAX490M, MAX491M MAX490C/E, MAX491C/E2090150MAX481, MAX485, MAX1487MAX490M, MAX491MMAX490C/E, MAX491C/E MAX481, MAX485, MAX1487Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pF MAX481 (Note 5)Figures 5 and 11, C RL = 15pF, S2 closedFigures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 6 and 8,R DIFF = 54Ω,C L1= C L2= 100pF Figures 6 and 10,R DIFF = 54Ω,C L1= C L2= 100pF CONDITIONS ns 510t SKEW ns50200600t SHDNTime to ShutdownMbps 2.5f MAX Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 103060t PLH 2050t LZ Receiver Disable Time from Low ns 2050t ZH Driver Input to Output Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low 2090200ns ns 134070t HZ t SKD Driver Disable Time from High |t PLH - t PHL |DifferentialReceiver Skewns 4070t LZ Driver Disable Time from Low ns 4070t ZL Driver Enable to Output Low 31540ns51525ns 31540t R , t F 2090200Driver Output Skew to Output t PLH , t PHL Receiver Input to Output4070t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERFigures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closedM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 4_______________________________________________________________________________________SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)3001000Figures 7 and 9, C L = 100pF, S2 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 5 and 11, C L = 15pF, S2 closed,A - B = 2VCONDITIONSns 40100t ZH(SHDN)Driver Enable from Shutdown toOutput High (MAX481)nsFigures 5 and 11, C L = 15pF, S1 closed,B - A = 2Vt ZL(SHDN)Receiver Enable from Shutdownto Output Low (MAX481)ns 40100t ZL(SHDN)Driver Enable from Shutdown toOutput Low (MAX481)ns 3001000t ZH(SHDN)Receiver Enable from Shutdownto Output High (MAX481)UNITS MINTYP MAX SYMBOLPARAMETERt PLH t SKEW Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFt PHL Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFDriver Input to Output Driver Output Skew to Output ns 100800ns ns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S2 closedt ZH(SHDN)Driver Enable from Shutdown to Output High2502000ns2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S1 closedt ZL(SHDN)Receiver Enable from Shutdown to Output Lowns 2500MAX483/MAX487, Figures 5 and 11,C L = 15pF, S2 closedt ZH(SHDN)Receiver Enable from Shutdown to Output Highns 2000MAX483/MAX487, Figures 7 and 9,C L = 100pF, S1 closedt ZL(SHDN)Driver Enable from Shutdown to Output Lowns 50200600MAX483/MAX487 (Note 5) t SHDN Time to Shutdownt PHL t PLH , t PHL < 50% of data period Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 5 and 11, C RL = 15pF, S2 closed Figures 5 and 11, C RL = 15pF, S1 closed Figures 7 and 9, C L = 15pF, S2 closed Figures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFFigures 7 and 9, C L = 15pF, S1 closed Figures 7 and 9, C L = 100pF, S1 closed Figures 7 and 9, C L = 100pF, S2 closed CONDITIONSkbps 250f MAX 2508002000Maximum Data Rate ns 2050t HZ Receiver Disable Time from High ns 25080020002050t LZ Receiver Disable Time from Low ns 2050t ZH Receiver Enable to Output High ns 2050t ZL Receiver Enable to Output Low ns ns 1003003000t HZ t SKD Driver Disable Time from High I t PLH - t PHL I DifferentialReceiver SkewFigures 6 and 10, R DIFF = 54Ω,C L1= C L2= 100pFns 3003000t LZ Driver Disable Time from Low ns 2502000t ZL Driver Enable to Output Low ns Figures 6 and 8, R DIFF = 54Ω,C L1= C L2= 100pFns 2502000t R , t F 2502000Driver Rise or Fall Time ns t PLH Receiver Input to Output2502000t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________530002.5OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGE525M A X 481-01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )1.515100.51.02.0203540450.90.1-50-252575RECEIVER OUTPUT LOW VOLTAGE vs.TEMPERATURE0.30.7TEMPERATURE (°C)O U T P U TL O W V O L T A G E (V )500.50.80.20.60.40100125-20-41.5 2.0 3.0 5.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGE-8-16M A X 481-02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )2.5 4.0-12-18-6-14-10-203.54.5 4.83.2-50-252575RECEIVER OUTPUT HIGH VOLTAGE vs.TEMPERATURE3.64.4TEMPERATURE (°C)O U T P UT H I G H V O L T A G E (V )0504.04.63.44.23.83.01001259000 1.0 3.0 4.5DRIVER OUTPUT CURRENT vs.DIFFERENTIAL OUTPUT VOLTAGE1070M A X 481-05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )2.0 4.05030806040200.5 1.5 2.53.5 2.31.5-50-2525125DRIVER DIFFERENTIAL OUTPUT VOLTAGEvs. TEMPERATURE1.72.1TEMPERATURE (°C)D I F FE R E N T I A L O U T P U T V O L T A G E (V )751.92.21.62.01.8100502.4__________________________________________Typical Operating Characteristics(V CC = 5V, T A = +25°C, unless otherwise noted.)NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICSNote 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to deviceground unless otherwise specified.Note 2:All typical specifications are given for V CC = 5V and T A = +25°C.Note 3:Supply current specification is valid for loaded transmitters when DE = 0V.Note 4:Applies to peak current. See Typical Operating Characteristics.Note 5:The MAX481/MAX483/MAX487 are put into shutdown by bringing RE high and DE low. If the inputs are in this state for lessthan 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 6___________________________________________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 5V, T A = +25°C, unless otherwise noted.)120008OUTPUT CURRENT vs.DRIVER OUTPUT LOW VOLTAGE20100M A X 481-07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )6604024801012140-1200-7-5-15OUTPUT CURRENT vs.DRIVER OUTPUT HIGH VOLTAGE-20-80M A X 481-08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )-31-603-6-4-2024-100-40100-40-60-2040100120MAX1487SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20608050020060040000140100-50-2550100MAX481/MAX485/MAX490/MAX491SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125100-50-2550100MAX483/MAX487–MAX489SUPPLY CURRENT vs. TEMPERATURE300TEMPERATURE (°C)S U P P L Y C U R R E N T (µA )257550020060040000125MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________7______________________________________________________________Pin DescriptionFigure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating CircuitM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487__________Applications InformationThe MAX481/MAX483/MAX485/MAX487–MAX491 and MAX1487 are low-power transceivers for RS-485 and RS-422 communications. The MAX481, MAX485, MAX490,MAX491, and MAX1487 can transmit and receive at data rates up to 2.5Mbps, while the MAX483, MAX487,MAX488, and MAX489 are specified for data rates up to 250kbps. The MAX488–MAX491 are full-duplex trans-ceivers while the MAX481, MAX483, MAX485, MAX487,and MAX1487 are half-duplex. In addition, Driver Enable (DE) and Receiver Enable (RE) pins are included on the MAX481, MAX483, MAX485, MAX487, MAX489,MAX491, and MAX1487. When disabled, the driver and receiver outputs are high impedance.MAX487/MAX1487:128 Transceivers on the BusThe 48k Ω, 1/4-unit-load receiver input impedance of the MAX487 and MAX1487 allows up to 128 transceivers on a bus, compared to the 1-unit load (12k Ωinput impedance) of standard RS-485 drivers (32 trans-ceivers maximum). Any combination of MAX487/MAX1487 and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481/MAX483/MAX485 and MAX488–MAX491 have standard 12k ΩReceiver Input impedance.Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 8_______________________________________________________________________________________Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating CircuitFigure 3. MAX489/MAX491 Pin Configuration and Typical Operating CircuitMAX483/MAX487/MAX488/MAX489:Reduced EMI and ReflectionsThe MAX483 and MAX487–MAX489 are slew-rate limit-ed, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 12 shows the dri-ver output waveform and its Fourier analysis of a 150kHz signal transmitted by a MAX481, MAX485,MAX490, MAX491, or MAX1487. High-frequency har-monics with large amplitudes are evident. Figure 13shows the same information displayed for a MAX483,MAX487, MAX488, or MAX489 transmitting under the same conditions. Figure 13’s high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers_______________________________________________________________________________________9_________________________________________________________________Test CircuitsFigure 4. Driver DC Test Load Figure 5. Receiver Timing Test LoadFigure 6. Driver/Receiver Timing Test Circuit Figure 7. Driver Timing Test LoadM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 10_______________________________________________________Switching Waveforms_________________Function Tables (MAX481/MAX483/MAX485/MAX487/MAX1487)Figure 8. Driver Propagation DelaysFigure 9. Driver Enable and Disable Times (except MAX488 and MAX490)Figure 10. Receiver Propagation DelaysFigure 11. Receiver Enable and Disable Times (except MAX488and MAX490)Table 1. TransmittingTable 2. ReceivingLow-Power Shutdown Mode (MAX481/MAX483/MAX487)A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled.In shutdown, the devices typically draw only 0.1µA of supply current.RE and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown.For the MAX481, MAX483, and MAX487, the t ZH and t ZL enable times assume the part was not in the low-power shutdown state (the MAX485/MAX488–MAX491and MAX1487 can not be shut down). The t ZH(SHDN)and t ZL(SHDN)enable times assume the parts were shut down (see Electrical Characteristics ).It takes the drivers and receivers longer to become enabled from the low-power shutdown state (t ZH(SHDN ), t ZL(SHDN)) than from the operating mode (t ZH , t ZL ). (The parts are in operating mode if the –R —E –,DE inputs equal a logical 0,1 or 1,1 or 0, 0.)Driver Output ProtectionExcessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short cir-cuits over the whole common-mode voltage range (see Typical Operating Characteristics ). In addition, a ther-mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.Propagation DelayMany digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 15–18 using Figure 14’s test circuit.The difference in receiver delay times, | t PLH - t PHL |, is typically under 13ns for the MAX481, MAX485,MAX490, MAX491, and MAX1487 and is typically less than 100ns for the MAX483 and MAX487–MAX489.The driver skew times are typically 5ns (10ns max) for the MAX481, MAX485, MAX490, MAX491, and MAX1487, and are typically 100ns (800ns max) for the MAX483 and MAX487–MAX489.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________1110dB/div0Hz5MHz500kHz/div10dB/div0Hz5MHz500kHz/divFigure 12. Driver Output Waveform and FFT Plot of MAX481/MAX485/MAX490/MAX491/MAX1487 Transmitting a 150kHz SignalFigure 13. Driver Output Waveform and FFT Plot of MAX483/MAX487–MAX489 Transmitting a 150kHz SignalM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 12______________________________________________________________________________________V CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CV CC = 5V T A = +25°CFigure 14. Receiver Propagation Delay Test CircuitFigure 15. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PHLFigure 16. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver t PLHPHL Figure 18. MAX483, MAX487–MAX489 Receiver t PLHLine Length vs. Data RateThe RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23.Figures 19 and 20 show the system differential voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 120Ωloads.Typical ApplicationsThe MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.Figures 21 and 22 show typical network applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23.To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possi-ble. The slew-rate-limited MAX483 and MAX487–MAX489are more tolerant of imperfect termination.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________13DIV Y -V ZRO5V 0V1V0V -1V5V 0V2µs/divFigure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable Figure 20. MAX483, MAX487–MAX489 System Differential Voltage at 110kHz Driving 4000ft of CableFigure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 NetworkM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 14______________________________________________________________________________________Figure 22. MAX488–MAX491 Full-Duplex RS-485 NetworkFigure 23. Line Repeater for MAX488–MAX491Isolated RS-485For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________15_______________Ordering Information_________________Chip TopographiesMAX481/MAX483/MAX485/MAX487/MAX1487N.C. RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND B N.C.V CCARE * Contact factory for dice specifications.__Ordering Information (continued)M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 16______________________________________________________________________________________TRANSISTOR COUNT: 248SUBSTRATE CONNECTED TO GNDMAX488/MAX490B RO 0.054"(1.372mm)0.080"(2.032mm)N.C. DIGND Z A V CCYN.C._____________________________________________Chip Topographies (continued)MAX489/MAX491B RO 0.054"(1.372mm)0.080"(2.032mm)DE DIGND Z A V CCYREMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers______________________________________________________________________________________17Package Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)S O I C N .E P SM A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers 18______________________________________________________________________________________Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)MAX481/MAX483/MAX485/MAX487–MAX491Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________19©2003 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.M A X 481/M A X 483/M A X 485/M A X 487–M A X 491/M A X 1487P D I P N .E PSPackage Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to /packages .)。

基于RS485的单片机设计

1个全双工的串行口，具有四种工作方式。可用来进行串行通讯，扩展并行I/O口，甚至与多个单片机相连构成多机系统，从而使单片机的功能更强且应用更广。
2.1.7 P1口、P2口、P3口、P4口
为4个并行8位I/O口。
2.1.8 特殊功能寄存器
共有21个，用于对片内的个功能的部件进行管理、控制、监视。实际上是
驱动器具有短路电流限制，并可以通过热关断电路将驱动器输出置为高阻状态，防止过度的功率损耗。接收器输入具有失效保护特性，当输入开路时，可以确保逻辑高电平输出。
MAX487与MAX1487具有四分之一单位负载的接收器输入阻抗，使得总线上最多可以有1 2 8 个MAX487/MAX1487收发器。使用MAX488-MAX491可以实现全双工通信，而MAX481、MAX483、MAX485、MAX487与MAX1487则为半双工应用设计。
由于单片机具有灵活高效的多机通信功能和价格优势应用越来越广泛但由于单片机的收发信号都是tti电平驱动能力和抗干扰性有限实用中常配合其它总线实现互联rs485总线就是其中之一
摘要
在多机通信领域．由于单片机具有灵活高效的多机通信功能和价格优势，应用越来越广泛，但由于单片机的收发信号都是TTI 电平，驱动能力和抗干扰性有限，实用中常配合其它总线实现互联，RS485总线就是其中之一。RS485总线是平衡差分传输，抗干扰性好，最远可传输4000 m，可互联多达128个单片机，非常适台组成多机通信系统。
2.1.3 程序存储器
由于受集成度限制，片内只读存储器一般容量较小，如果片内的只读存储器的容量不够，则需用扩展片外的只读存储器，片外最多可外扩至64k字节。
2.1.4 中断系统
具有5个中断源，2级中断优先权。
2.1.5 定时器/计数器