LM45B中文资料

TL H 11754LM45B LM45C SOT-23 Precision Centigrade Temperature SensorsMay1995 LM45B LM45CSOT-23Precision Centigrade Temperature SensorsGeneral DescriptionThe LM45series are precision integrated-circuit tempera-ture sensors whose output voltage is linearly proportional tothe Celsius(Centigrade)temperature The LM45does notrequire any external calibration or trimming to provide accu-racies of g2 C at room temperature and g3 C over a fullb20to a100 C temperature range Low cost is assured bytrimming and calibration at the wafer level The LM45’s lowoutput impedance linear output and precise inherent cali-bration make interfacing to readout or control circuitry espe-cially easy It can be used with a single power supply or withplus and minus supplies As it draws only120m A from itssupply it has very low self-heating less than0 2 C in stillair The LM45is rated to operate over a b20 to a100 Ctemperature rangeApplicationsY Battery ManagementY FAX MachinesY PrintersY Portable Medical InstrumentsY HVACY Power Supply ModulesY Disk DrivesY ComputersY AutomotiveFeaturesY Calibrated directly in Celsius(Centigrade)Y Linear a10 0mV C scale factorY g3 C accuracy guaranteedY Rated for full b20 to a100 C rangeY Suitable for remote applicationsY Low cost due to wafer-level trimmingY Operates from4 0V to10VY Less than120m A current drainY Low self-heating 0 20 C in still airY Nonlinearity only g0 8 C max over tempY Low impedance output 20X for1mA load Connection DiagramSOT-23TL H 11754–1Top ViewSee NS Package Number M03B(JEDEC Registration TO-236AB)SOT-23Order DeviceNumber Marking Supplied AsLM45BIM3T4B250Units on Tape and ReelLM45BIM3X T4B3000Units on Tape and ReelLM45CIM3T4C250Units on Tape and ReelLM45CIM3X T4C3000Units on Tape and Reel Typical ApplicationsTL H 11754–3FIGURE1 Basic Centigrade TemperatureSensor(a2 5 C to a100 C)TL H 11754–4Choose R1e b V S 50m AV OUT e(10mV C c Temp C)V OUT e a1 000mV at a100 Ce a250mV at a25 Ce b200mV at b20 CFIGURE2 Full-Range CentigradeTemperature Sensor(b20 C to a100 C)C1995National Semiconductor Corporation RRD-B30M75 Printed in U S AAbsolute Maximum Ratings(Note1)Supply Voltage a12V to b0 2V Output Voltage a V S a0 6V to b1 0V Output Current10mA Storage Temperature b65 C to a150 C Lead TemperatureSOT Package(Note2)Vapor Phase(60seconds)215 C Infrared(15seconds)220 C ESD Susceptibility(Note3)Human Body Model2000V Machine Model TBD Operating Ratings(Note1)Specified Temperature Range(Note4)T MIN to T MAX LM45B LM45C b20 C to a100 C Operating Temperature RangeLM45B LM45C b40 C to a125 C Supply Voltage Range(a V S)a4 0V to a10VElectrical Characteristics Unless otherwise noted these specifications apply for a V S e a5Vdc and I LOAD e a50m A in the circuit of Figure2 These specifications also apply from a2 5 C to T MAX in the circuit of Figure1for a V S e a5Vdc Boldface limits apply for T A e T J e T MIN to T MAX all other limits T A e T J e a25 C unless otherwise notedParameter ConditionsLM45B LM45C(Limit)Units Typical Limit Typical Limit(Note5)(Note5)Accuracy T A e a25 C g2 0g3 0 C(max) (Note6)T A e T MAX g3 0g4 0 C(max)T A e T MIN g3 0g4 0 C(max)Nonlinearity T MIN s T A s T MAX g0 8g0 8 C(max) (Note7)Sensor Gain T MIN s T A s T MAX a9 7a9 7mV C(min) (Average Slope)a10 3a10 3mV C(max) Load Regulation(Note8)0s I L s a1mA g35g35mV mA(max)Line Regulation a4 0V s a V S s a10V g0 80g0 80mV V(max) (Note8)g1 2g1 2mV V(max)Quiescent Current a4 0V s a V S s a10V a25 C120120m A(max) (Note9)a4 0V s a V S s a10V160160m A(max)Change of Quiescent4 0V s a V S s10V2 02 0m A(max) Current(Note8)Temperature Coefficienta2 0a2 0m A Cof Quiescent CurrentMinimum Temperature In circuit ofa2 5a2 5 C(min) for Rated Accuracy Figure1 I L e0Long Term Stability(Note10)T J e T MAX for1000hours g0 12g0 12 CNote1 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditionsNote2 See AN-450‘‘Surface Mounting Methods and Their Effect on Product Reliability’’or the section titled‘‘Surface Mount’’found in a current National Semiconductor Linear Data Book for other methods of soldering surface mount devicesNote3 Human body model 100pF discharged through a1 5k X resistor Machine model 200pF discharged directly into each pinNote4 Thermal resistance of the SOT-23package is260 C W junction to ambient when attached to a printed circuit board with2oz foil as shown in Figure3 Note5 Limits are guaranteed to National’s AOQL(Average Outgoing Quality Level)Note6 Accuracy is defined as the error between the output voltage and10mv C times the device’s case temperature at specified conditions of voltage current and temperature(expressed in C)Note7 Nonlinearity is defined as the deviation of the output-voltage-versus-temperature curve from the best-fit straight line over the device’s rated temperature rangeNote8 Regulation is measured at constant junction temperature using pulse testing with a low duty cycle Changes in output due to heating effects can be computed by multiplying the internal dissipation by the thermal resistanceNote9 Quiescent current is measured using the circuit of Figure1Note10 For best long-term stability any precision circuit will give best results if the unit is aged at a warm temperature and or temperature cycled for at least46 hours before long-term life test begins This is especially true when a small(Surface-Mount)part is wave-soldered allow time for stress relaxation to occur2Typical Performance CharacteristicsTo generate these curves the LM45was mounted to a printed circuit board as shown in Figure 3Junction to AirThermal Resistance Thermal Time Constantwith Heat Sink (Figure 3)Thermal Response in Still Air with Heat Sinkin Stirred Oil Bath Thermal Response vs TemperatureStart-Up Voltage (In Circuit of Figure 1)vs TemperatureQuiescent Current (In Circuit of Figure 2)vs TemperatureQuiescent Current (Guaranteed)Accuracy vs Temperature Noise Voltagevs Supply CurrentSupply Voltage Start-Up ResponseTL H 11754–23FIGURE 3 Printed Circuit Board Used for Heat Sink to Generate All Curves Square Printed Circuit Boardwith 2oz Foil or SimilarTL H 11754–53ApplicationsThe LM45can be applied easily in the same way as other integrated-circuit temperature sensors It can be glued or cemented to a surface and its temperature will be within about 0 2 C of the surface temperatureThis presumes that the ambient air temperature is almost the same as the surface temperature if the air temperature were much higher or lower than the surface temperature the actual temperature of the LM45die would be at an inter-mediate temperature between the surface temperature and the air temperatureTo ensure good thermal conductivity the backside of the LM45die is directly attached to the GND pin The lands and traces to the LM45will of course be part of the printed circuit board which is the object whose temperature is be-ing measured These printed circuit board lands and traces will not cause the LM45s temperature to deviate from the desired temperatureAlternatively the LM45can be mounted inside a sealed-end metal tube and can then be dipped into a bath or screwedinto a threaded hole in a tank As with any IC the LM45and accompanying wiring and circuits must be kept insulated and dry to avoid leakage and corrosion This is especially true if the circuit may operate at cold temperatures where condensation can occur Printed-circuit coatings and var-nishes such as Humiseal and epoxy paints or dips are often used to insure that moisture cannot corrode the LM45or its connectionsTemperature Rise of LM45Due to Self-Heating(Thermal Resistance)SOT-23 SOT-23no heat sink small heat finStill air 450 C W 260 C W Moving air 180 C WHeat sink used is square printed circuit board with 2oz foil with part attached as shown in Figure 3 Part soldered to 30gauge wireTypical ApplicationsCAPACITIVE LOADSLike most micropower circuits the LM45has a limited ability to drive heavy capacitive loads The LM45by itself is able to drive 500pF without special precautions If heavier loads are anticipated it is easy to isolate or decouple the load with a resistor see Figure 4 Or you can improve the tolerance of capacitance with a series R-C damper from output to ground see Figure 5Any linear circuit connected to wires in a hostile environ-ment can have its performance affected adversely by in-tense electromagnetic sources such as relays radio trans-mitters motors with arcing brushes SCR transients etc as its wiring can act as a receiving antenna and its internal junctions can act as rectifiers For best results in such cas-es a bypass capacitor from V IN to ground and a series R-C damper such as 75X in series with 0 2or 1m F from output to ground as shown in Figure 5 are often usefulTL H 11754–8FIGURE 4 LM45with Decoupling from Capacitive LoadTL H 11754–9FIGURE 5 LM45with R-C DamperTL H 11754–12FIGURE 6 Temperature Sensor Single Supply b 20 C to a 100 C4Typical Applications(Continued)TL H 11754–14FIGURE7 4-to-20mA Current Source(0 C to a100 C)TL H 11754–15FIGURE8 Fahrenheit ThermometerTL H 11754–16FIGURE9 Centigrade Thermometer(Analog Meter)TL H 11754–17FIGURE10 Expanded Scale Thermometer(50 to80 Fahrenheit for Example Shown)TL H 11754–18FIGURE11 Temperature To Digital Converter(Serial Output)(a128 C Full Scale)5Typical Applications(Continued)TL H 11754–19FIGURE12 Temperature To Digital Converter(Parallel TRI-STATE Outputs forStandard Data Bus to m P Interface)(128 C Full Scale)TL H 11754–20 e1%or2%film resistor-Trim R B for V B e3 075V-Trim R C for V C e1 955V-Trim R A for V A e0 075V a100mV C c T ambient-Example V A e2 275V at22 CFIGURE13 Bar-Graph Temperature Display(Dot Mode)6Typical Applications(Continued)TL H 11754–21 FIGURE14 LM45With Voltage-To-Frequency Converter And Isolated Output(2 5 C to a100 C 25Hz to1000Hz)Block DiagramTL H 11754–227L M 45B L M 45C S O T -23P r e c i s i o n C e n t i g r a d e T e m p e r a t u r e S e n s o r sPhysical Dimensions inches (millimeters)SOT-23Molded Small Outline Transistor Package (M3)Order Number LM45BIM3 LM45BIM3X LM45CIM3or LM45CIM3XNS Package Number M03B (JEDEC Registration TO-236AB)LIFE SUPPORT POLICYNATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION As used herein 1 Life support devices or systems are devices or 2 A critical component is any component of a life systems which (a)are intended for surgical implant support device or system whose failure to perform can into the body or (b)support or sustain life and whose be reasonably expected to cause the failure of the life failure to perform when properly used in accordance support device or system or to affect its safety or with instructions for use provided in the labeling can effectivenessbe reasonably expected to result in a significant injury to the userNational 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