ads1278
ADS1278使用总结
1.数据输出格式2.引脚说明3.速度模式设置芯片一共有4种速度模式，下图为4种模式的最大采样率及功耗表：以上四种工作模式用MODE1和MODE0控制，其对应关系如下表，当为High-Speed时，fclk最大可为37MHz，其他三种模式时，最大输入时钟为27MHz。
且当fclk>27MHz时，只能采用Frame-Sync方式读取数据。
在High-Speed模式下，不同的时钟频率(fclk)对DVDD和参考电压（Vref）的的要求也不一样，具体如下表所示：ADS1278的数据输出率与fclk具有固定的比例关系，且Low-Power和Low-Speed模式下，CLKDIV能够对fclk分频。
另外两种模式下，CLKDIV必须为1，具体关系如下表所示：注意：在High-Speed模式下，若为TDM方式输出，因为8个通道均通过OUT1输出且数据为24bits，故必须保证clk=SCLK4.输出方式设置采样数据可通过两种方式输出SPI方式和Frame-Sync方式。
输出方式由FORMAT[2:0]控制，如下图所示。
TDM表示8个通道数据全部由DUOT1输出，CH1在前，CH8在后。
此时若DATA POSITION 为Dynamic则表示：若某通道关闭，则该通道仍然输出，输出数据为0。
若DATA POSITION 为Fixed，则如果某通道关闭，则该通道不输出，直接输出下一通道数据。
5.供电电压ADS1278需要3个电压DVDD、IOVDD和AVDD。
其中DVDD电压为1.65-1.95V（当32.768MHz < f CLK ≤37MHz时，DVDD须为2.0-2.2V）;IOVDD电压为1.65V-3.6V; AVDD电压须为4.75V-5.25V。
且每个电源引脚处均须放置一个10UF钽电容和0.1UF陶瓷电容。
且ADS1278严格要求电源稳定，不可与其它易产生电源峰值的器件共用电源。
●电路设计：DVDD和IOVDD采用TPS730xx系列LDO电源芯片。
ADS1278EVM-PDK;ADS1278EVM;中文规格书,Datasheet资料
User's GuideSBAU129D–November2007–Revised April2010 ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,andADS1278EVM-PDKADS1178EVM(Left)and ADS1178EVM-PDK(Right)This user's guide describes the characteristics,operation,and use of the ADS1178EVM and ADS1278EVM,both by themselves and as part of the ADS1178EVM-PDK or ADS1278EVM-PDK.These evaluation modules(EVMs)are evaluation boards for the ADS1278,a24-bit multi-channel,delta-sigma analog-to-digital converter(ADC),and the ADS1178,a16-bit version of the ADS1278.The EVM allows evaluation of all aspects of the ADS1178or plete circuit descriptions,schematic diagrams,and bills of material are included in this document.The following related documents are available through the Texas Instruments web site at .EVM-Compatible Device Data SheetsADCPro is a trademark of Texas Instruments.Microsoft,Windows are registered trademarks of Microsoft Corporation.I2C is a trademark of NXP Semiconductors,Inc.All other trademarks are the property of their respective owners.1 SBAU129D–November2007–Revised April2010ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK Submit Documentation FeedbackContents1EVM Overview (4)2Analog Interface (4)3Digital Interface (5)4Power Supplies (7)5Voltage Reference (8)6Power-Down,Mode,and Format Control (8)7Clock Source (9)8EVM Operation (9)9ADS1278EVM-PDK Kit Operation (13)10Evaluating Performance with the ADCPro Software (26)11Schematics and Layout (31)List of Figures1Connector J2 (6)2Connectors J15,J16 (7)3Connector J1 (8)4Switch S1 (8)5Jumper J19 (9)6Amplifier Selection Switches (10)7ADS1278EVM Default Jumper Locations (12)8MMB0Initial Setup (14)9Connecting ADS1278EVM to MMB0 (15)10Connecting an AC Adapter (16)11Laboratory Power-Supply Connection (17)12NI-VISA Driver Installation (18)13NI-VISA Driver Installation Question (19)14NI-VISA Driver Installing (19)15NI-VISA Driver Complete Installation (20)16NI-VISA Driver Verification Using Device Manager (20)17ADCPro Software Start-up Display Window (21)18ADS1278EVM-PDK Plug-In Display Window (22)19Install New Driver Wizard Screen1 (23)20Install New Driver Wizard Screen2 (23)21Install New Driver Wizard Screen3 (24)22Install New Driver Wizard Screen4 (24)23Install New Driver Wizard Screen5 (25)24USBStyx Driver Verification Using Device Manager (25)25Channel Enable (26)26Manual Channel Control (27)27Clock Settings and Mode (28)28Operating Mode (29)29Output Data Format (29)30Progress Bar While Collecting Data (30)List of Tables1J9/J7:Analog Interface Pinout (5)2J8:Supplemental Analog Interface Pinout (5)3J5:Serial Interface Pins (6)4J3Configuration:Power-Supply Input (7)2ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK SBAU129D–November2007–Revised April2010Submit Documentation Feedback5J15+10V Selection (7)6J16–10V Selection (7)7List of Switches (12)8Operating Modes:Clock Frequency (27)9ADS1278EVM Bill of Materials (31)3 SBAU129D–November2007–Revised April2010ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK Submit Documentation FeedbackEVM Overview 1EVM Overview1.1FeaturesADS1178EVM/ADS1278EVM Features:•Contains all support circuitry needed for the ADS1178/ADS1278•+10V and–10V generated from the+5V supply or supplied externally•Voltage reference options:external or onboard•Clock options:External clock source or27MHz onboard crystal oscillator•GPIO access•Compatible with the TI Modular EVM SystemADS1178EVM-PDK/ADS1278EVM-PDK Features:•Easy-to-use evaluation software for Microsoft®Windows®XP•Data collection to text files•Built-in analysis tools including scope,FFT,and histogram displays•Complete control of board settings•Easily expandable with new analysis plug-in tools from Texas InstrumentsFor use with a computer,the ADS1178EVM-PDK or ADS1278EVM-PDK is available.This kit combines the ADS1178EVM/ADS1278EVM board with the DSP-based MMB0motherboard,and includes ADCPro™software for evaluation.The MMB0motherboard allows the ADS1178EVM/ADS1278EVM to be connected to the computer via an available USB port.This manual shows how to use the MMB0as part of theADS1178EVM-PDK/ADS1278EVM-PDK,but does not provide technical details about the MMB0itself.ADCPro is a program for collecting,recording,and analyzing data from ADC evaluation boards.It is based on a number of plug-in programs,so it can be expanded easily with new test and data collection plug-ins.The ADS1178EVM-PDK/ADS1278EVM-PDK is controlled by a plug-in running in ADCPro.For moreinformation about ADCPro,see the ADCPro™Analog-to-Digital Converter Evaluation Software User'sGuide(/lit/ug/sbau128/sbau128.pdf),available for download for the TI web site.This manual covers the operation of both the ADS1178EVM/ADS1278EVM and theADS1178EVM-PDK/ADS1278EVM-PDK.Throughout this document,the abbreviation EVM and the term evaluation module are synonymous with the ADS1178EVM/ADS1278EVM.For clarity of reading,thismanual will refer only to the ADS1278EVM or ADS1278EVM-PDK,but operation of the EVM and kit for the ADS1178is identical,unless otherwise noted.1.2IntroductionThe ADS1278EVM is an evaluation module built to the TI Modular EVM System specification.It can be connected to any modular EVM system interface card.The ADS1278EVM is available as a stand-alone printed circuit board(PCB)or as part of theADS1278EVM-PDK,which includes an MMB0motherboard and software.As a stand-alone PCB,theADS1278EVM is useful for prototyping designs and firmware.Note that the ADS1278EVM has no microprocessor and cannot run software.To connect it to a computer, some type of interface is required.2Analog InterfaceFor maximum flexibility,the ADS1278EVM is designed for easy interfacing to multiple analog sources.Samtec part numbers SSW-110-22-F-D-VS-K and TSM-110-01-T-DV-P provide a convenient10-pin,dual-row,header/socket combination at J9.This header/socket provides access to the analog input pins of the ADS1278.Consult Samtec at or call1-800-SAMTEC-9for a variety of mating connector options.These signals can also be connected to the terminal block J7.In addition to J9(and J7),terminal block J8also provides additional analog inputs to accommodate the large number of input channels available on the ADS1278.4ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK SBAU129D–November2007–Revised April2010Submit Documentation Feedback Digital Interface Most of the pins on J7,J8and J9are directly connected,with no filtering or e appropriate caution when handling these pins.Table1and Table2summarize the pinouts for analog interfaces J9/J7 and J8,respectively.Table1.J9/J7:Analog Interface PinoutPin Number Signal DescriptionJ9.1,J7-2A1N AINN1,ADS1278J9.2,J7-3A1P AINP1,ADS1278J9.3,J7-4A2N AINN2,ADS1278J9.4,J7-5A2P AINP2,ADS1278J9.5,J7-6A3N AINN3,ADS1278J9.6,J7-7A3P AINP3,ADS1278J9.7,J7-8A4N AINN4,ADS1278J9.8,J7-9A4P AINP4,ADS1278J9.18EXTREFN External Reference source input(–side ofdifferential input)J9.20EXTREFP External Reference source input(+side ofdifferential input)J9.10-16(even)Unused—J9.15Unused—J9.9-19(odd),J7-1AGND Analog ground connections(except J1.15)Table2.J8:Supplemental Analog Interface PinoutPin Number Signal DescriptionJ8.1GND Analog groundJ8.2A5N AIN5N,ADS1278J8.3A5P AIN5P,ADS1278J8.4A6N AIN6N,ADS1278J8.5A6P AIN6P,ADS1278J8.6A7N AIN7N,ADS1278J8.7A7P AIN7P,ADS1278J8.8A8N AIN8N,ADS1278J8.9A8P AIN8P,ADS12783Digital Interface3.1Serial Data InterfaceThe ADS1278EVM is designed to easily interface with multiple control platforms.Samtec part numbers SSW-110-22-F-D-VS-K and TSM-110-01-T-DV-P provide a convenient10-pin,dual-row,header/socket combination at J5.This header/socket provides access to the digital control and serial data pins of theADC.Consult Samtec at or call1-800-SAMTEC-9for a variety of matingconnector options.5 SBAU129D–November2007–Revised April2010ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK Submit Documentation FeedbackDigital Interface All logic levels on J5are3.3V CMOS,except for the I2C™pins.These pins conform to3.3V I2C rules.Table3describes the J5serial interface pins.Table3.J5:Serial Interface PinsPin No.Pin Name Signal Name I/O Type Pullup FunctionJ5.1CNTL SYNC In High—J5.2GPIO0MODE0In High—J5.3CLKX SCLK In None ADS1278SPI clock J5.4DGND DGND In/Out None Digital groundJ5.5CLKR CLKR Out None SCLK clockJ5.6GPIO1MODE1In High—J5.7FSX DRDY/FSYNC In/Out Low—J5.8GPIO2FORMAT0In High—J5.9FSR DRDY/FSYNC In/Out None—J5.10DGND DGND In/Out None Digital groundJ5.11DX DIN In None ADS1278SPI datain J5.12GPIO3FORMAT1In High—J5.13DR DOUT1Out None ADS1278data out J5.14GPIO4FORMAT2In None—J5.15/INT DRDY/FSYNC Out None—J5.16SCL SCL I2C N/A I2C clockJ5.17TOUT CLK In None Can be used toprovide a clock froma processorJ5.18DGND DGND In/Out None Digital groundJ5.19GPIO5CLK Select—None—J5.20SDA SDA I2C N/A I2C dataMany pins on J5have weak pull-up/down resistors.These resistors provide default settings for many of the control pins.Many pins on J5correspond directly to ADS1278pins.See the ADS1278product data sheet for complete details on these pins.3.2Data OutputMost data communications are directed through DOUT1.The data from all eight channels can beobserved on the DOUT1pin using the TDM mode.That is the signal that is used by theADS1278EVM-PDK to read back and display all the channels.All the data output signals(DOUT1toDOUT8)can be monitored on J2.Figure1illustrates the pinout for J2.Figure1.Connector J26ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK SBAU129D–November2007–Revised April2010Submit Documentation Feedback Power Supplies 4Power SuppliesJ3is the power-supply input connector.Table4lists the configuration details for J3.Analog inputs to the ADC can be applied directly to the device(see Section8.1,Analog Input),bypassing the onboardamplifiers,and in this case only+5V and+3.3V are required to power the EVM.If the amplifiers are used, an additional bipolar supply is needed to power them.The EVM includes a switching power supply togenerate a+10V and–10V supply.For optimum noise performance,the external supplies(+VA and–VA) should be used.Table4.J3Configuration:Power-Supply InputPin No.Pin Name Function RequiredJ3.1+VA+10V to+15V Yes,unless onboard+10V isused.J3.2–VA-10V to–15V Yes,unless onboard–10V isused.J3.3+5VA+5V analog supply AlwaysJ3.4–5VA–5V analog supply NoJ3.5DGND Digital ground input YesJ3.6AGND Analog ground input YesJ3.7+1.8VD 1.8V digital supply NoJ3.8VD1Not used NoJ3.9+3.3VD 3.3V digital supply AlwaysJ3.10+5VD+5V Used to generate+10V/–10V The1.8V for DVDD comes from the voltage regulator U16using3.3V as the source voltage input.All of the power supplies AVDD(+5V),DVDD(1.8V),and IOVDD(3.3V)have corresponding jumpers J10, J11(AVDD),J13(DVDD)and J14(IOVDD)that can be replaced with a current meter to measure therespective supply currents.4.1Bipolar Power OptionsJ15and J16require a jumper to select the voltage used by the onboard amplifiers.The external voltages can range from10V to15V.The onboard voltage is always10V.Table5and Table6list the options for J15and J16,respectively.Figure2shows the pinout for connectors J15and J16.Table5.J15+10V SelectionJumper Name Function1-2(OB)+10V Select the+10V that is generatedon the EVM2-3(EXT)+VA Select the external+VA voltageTable6.J16–10V SelectionJumper Name Function1-2–10V Select the–10V that is generatedon the EVM2-3–VA Select the external–VA voltageFigure2.Connectors J15,J167 SBAU129D–November2007–Revised April2010ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK Submit Documentation FeedbackVoltage Reference 5Voltage ReferenceThe ADS1278EVM has three sources for the reference voltage.Jumper J1can select the voltage from either the REF3125(U1)or REF5025(U2).The reference from either source is filtered and buffered by U3A.Switch S1chooses either the onboard reference or the external reference voltage that is connected to the reference pins of J9.Figure3illustrates the pinout for connector J1.Figure4shows switch S1as it appears on the EVM.Figure3.Connector J1Figure4.Switch S16Power-Down,Mode,and Format ControlThe ADS1278has several pins to control the power-down of individual channels,and mode and format for the digital interface.These pins are controlled on the EVM either through software or hardware(usingswitches S10and S11).For users of the ADS1278EVM as a stand-alone module,these pins may be pulled high or low through DIP switches S10and S11.Refer to the ADS1278product data sheet for complete details on these pins and which state sets which options.For use in the ADS1278EVM-PDK,the state of these pins is controlled by software,using the I2C portexpander on the EVM.When used in the ADS1278EVM-PDK,the DIP switches S10and S11must all be switched so that they are down,toward the center of the board.The ADS1278EVM-PDK software willcheck at startup to verify that these switches are set correctly,and will generate an error message if they are not.However,it cannot detect if the switches are changed after startup.CAUTIONWhen using the EVM as part of the ADS1278EVM-PDK,the DIP switches S10and S11must all be switched so that they are down,toward the center of theboard.Failure to do so may damage the EVM.8ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK SBAU129D–November2007–Revised April2010Submit Documentation Feedback Clock Source 7Clock SourceThe ADS1278clock can come from one of several sources:the onboard27MHz crystal oscillator,a clock supplied by a processor on the TOUT pin(J5.17),or an external clock source connected to J18.1(ground) and J18.2(signal).If the onboard27MHz oscillator is selected,the device can be run in the high-speed mode,thehigh-resolution mode,the low-power mode,or low-speed modes with CLKDIV set to1.If the performance of the device must be explored with CLKDIV set to0in the low-power and low-speed modes,an external clock must be provided to the board,either using the TOUT connection or having an external clock source connected to J18.The same condition is true if frequencies other than the27MHz provided by theonboard oscillator must be investigated.7.1Usage in PDKIf using the ADS1278EVM as part of the ADS1278EVM-PDK,J19should not have any pins shorted.Remove any shorting blocks on jumper J19.The ADS1278EVM-PDK software will allow selection of the clock source under software control(this is accomplished by using port05of the I2C expander U17).The software allows selection of the onboard27MHz oscillator,or a clock provided by a PLL on the MMB0that directly drives the appropriate CLK pins of the interface,or an external,customer-supplied clock.If anexternal clock is selected with the software,this clock must be provided on J18.Note that if the external clock is selected and no clock is provided,the software may hang waiting for data from the converter.7.2Usage as a Stand-Alone EVMIf using the EVM in your own system and not with the PDK hardware and software,observe the following recommendations:•J17should be removed if the external clock source is used and the TOUT pin is still driven by a processor in order to avoid conflicts.•Jumper J19can be used to always select the27MHz crystal(IOVDD position)or allow the onboard/external clock selection to be controlled by GPIO5(J5.19),as shown in Figure5.Figure5.Jumper J198EVM OperationThe following section provides information on the analog input,digital control,and general operatingconditions of the ADS1278EVM.8.1Analog InputFour of the analog input sources(channels1–4)can be applied directly to J9(top or bottom side)orthrough signal-conditioning modules available for the modular EVM system.Terminal block J7isconnected in parallel with the analog signal connections to J9.The additional four channel sources(5-8) can be applied to the terminal block J8.Each input signal can be selected to connect directly to the analog inputs of the ADS1278or they can use the OPA1632buffers that are provided.Switches S2–9can be switched away from the ADS1278to select the Terminal Block(TBK)or towards the ADS1278to select the Amplifier(AMP)for the analog inputs1 through8,as shown in Figure6.9 SBAU129D–November2007–Revised April2010ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK Submit Documentation FeedbackEVM Operation Figure6.Amplifier Selection Switches8.2Digital ControlThe digital control signals can be applied directly to J5(top or bottom side).The modular ADS1278EVM can also be connected directly to a DSP or microcontroller interface board,such as the5-6K Interface or HPA-MCUInterface boards available from Texas Instruments,or the MMB0if purchased as part of theADS1278EVM-PDK.For a list of compatible interface and/or accessory boards for the EVM or theADS1278,see the relevant product folder on the TI web site.Some of the digital signals are controlled directly with pins on J5.Other signals such as the Power Down controls can only be controlled with slide switches or by U17and U18that are set up and read using the I2C signals on pins16and18of J5.The Format and Mode pins can be controlled by all three methods(slide switches,GPIO pins on J5,and the I2C control from U17).10ADS1178EVM,ADS1278EVM,ADS1178EVM-PDK,and ADS1278EVM-PDK SBAU129D–November2007–Revised April2010Submit Documentation Feedback分销商库存信息:TIADS1278EVM-PDK ADS1278EVM。
ADS1274中文版
ADS1274四方形封装/八进制，同步采样，24位ΔΣ模数转换器特性：同步采样四/八通道；高达144K采样率交流特性—70KHz带宽，111dB信噪比（高分辨率模式），-108dB谐波失真；直流特性：温漂——0.8uV每摄氏度，增益漂移——1.3ppm每摄氏度；可选择的工作模式：高速模式——144kSPS，106dB信噪比，高分辨率模式——52kSPS，111dB信噪比，低功耗模式——52kSPS，31mW/ch低速模式——10kSPS，7mW/ch；线性相位数字滤波器；SPI或帧同步，串行接口；低采样误差；调制解调器输出选项（数字滤波器带宽）；模拟供电：5V；数字内核：1.8V；IO口供电：1.8V to 3.3V；应用：振动分析仪；多通道数据采集；音箱动态仪表；压力传感器描述：基于单通道ADS1271，ADS1274和ADS1278都是24位ΔΣ型模数转换器，拥有高达144k采样率，允许四/八通道同步采集。
两款芯片使用的是同样的封装，允许交叉扩展。
传统来说，工业级ΔΣ在使用数字滤波器和通带衰减的情况下能提供很好的失调表现。
结果，他们限制了信号带宽，然后就非常适合直流测量。
高分辨率的ADC在音频应用中提供了很大的可使用的带宽，但是这些失调和漂移特性，对微弱信号是非常有意义的相比于传统的工业计数器。
ADS1274和ADS1278联合了这些转换器，允许高精度的工业直流和交流测量。
高阶、斩波稳零模块在低通带噪声的情况下成功的获得了非常小的漂移。
片上抽取滤波器抑制模块和通带之外的噪声。
ADC芯片提供了高达90%的乃奎斯特采样率的信号带宽，和小于0.005dB的通带纹波。
四个工作模块允许速度、分辨率和功耗的最优选择。
所有的功能都是通过引脚来控制，芯片内没有需要编写的寄存器。
ADS1274引脚图SPI时序格式综述ADS1274和ADS1278都是在单通道模数转换器ADS1271的基础上改进而来的。
他们既提供了了杰出的直流特性又有卓越的交流表现。
ADS1278使用总结
ADS1278使用总结首先，ADS1278的输入模拟信号范围为±VREF，VREF取决于芯片的工作电压和参考电压的选择。
在使用时，需根据具体的信号范围和精度要求来设置VREF。
如果输入信号超出范围，可能会导致转换结果不准确或损坏芯片。
其次，ADS1278具有多通道输入功能。
在使用多通道时，需要在开机前设置输入通道的配置寄存器。
通过设置寄存器中的MUX位来选择输入通道，并根据需要配置差分输入模式或单端输入模式。
多通道输入允许同时转换多个信号源，提高了系统的灵活性和效率。
另外，ADS1278支持多种不同的采样速率和分辨率。
在使用时，需要根据具体应用需求来设置采样速率和分辨率。
较高的采样速率可以提供更高的信号质量，但会增加功耗和数据处理的复杂性。
较高的分辨率可以提高信号的准确性，但会增加转换时间。
因此，在设置采样速率和分辨率时需要权衡功耗、数据处理和信号质量等因素。
此外，ADS1278还具有内部参考电压和PGA（可编程增益放大器）功能。
内部参考电压提供了一个稳定和精确的参考电压源，可用于校准和调整系统。
PGA功能允许用户对输入信号进行放大，以适应不同范围和灵敏度的输入信号。
这些功能的合理设置可以进一步提高系统的性能和灵活性。
在系统设计中，还需要合理布局和连接电源和信号线。
由于ADS1278对电源纹波和干扰敏感，因此需要提供稳定的电源，并采取适当的滤波和终端电容措施来减少电源纹波和干扰。
对于输入信号线，需要保持良好的屏蔽和阻抗匹配，并避免与高频信号线、电源线和开关线路的干扰。
这些措施可以降低噪声和误差，保证转换结果的准确性和稳定性。
最后，在使用ADS1278时，还需要注意使用和存储转换结果的方式。
转换结果通过SPI接口传输给外部设备，可以通过单次转换模式或连续转换模式来获取结果。
在使用过程中，需要合理设置SPI时钟频率和数据传输模式，并注意数据的解析和处理。
对于长时间存储转换结果的应用，还需要考虑数据的格式和容量，并采取适当的压缩和存储策略。
DC1278 快速入门指南说明书
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 12786-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADCLTC2351-14 DESCRIPTIONDemonstration circuit 1278 features the LTC2351-14 6-channel, 14-Bit, simultaneous sampling ADC. Total throughput is 1.5MSPS; 250KSPS per channel, with a typical channel-to-channel aperture skew of 200ps. The board is designed to be used with the DC890B Fast DAACS data collection board to show the AC performance of the LTC2351-14. Alternatively, the board can be directly connected to an application to evaluate the ADC’s performance.Design files for this circuit board are available. Call the LTC factory.LTC is a trademark of Linear Technology CorporationQUICK START PROCEDURE BASIC CONNECTIONSConnect DC1278 to a DC890B USB High Speed Data Collection Board using connector J2. Connect DC890B to a host PC with a standard USB A/B cable. Apply 5-7V DC to the VIN and GND terminals. Apply a 25MHz 3.3Vp-p sine wave or square wave to connec-tor J3. Note that J3 has a 50 ohm termination resistor to ground. CH0-CH5 are provided through connector J1 (See schematic for details.). Run the QuickEval II (Pscope.exe) evaluation software supplied with DC890 or download it from /software.Figure 1. CONNECTION DIAGRAM 40 pin AnalogSignal Connector (Refer to Schematic)To DC890BController Master clock at 98x conversion rate, 3.3Vpp Sine or Square wave (See Hardware Setup Section)5-7VDC SupplyFigure 2.SOFTWARE SCREENSHOTSOFTWARE CONFIGURATIONCONFIGURE DEVICEThe Pscope software should automatically config-ure itself after detecting the demo board. To change from Bipolar to Unipolar mode it will be necessary to manually configure the software. In the CONFIGURE menu (See Figure 3) select Device, which will bring up another window. In this window, select User Configure and adjust the other settings as follows:Bits: 14Alignment: 14Bipolar: Checked if BIP jumper is set high, Un-Checked if BIP jumper is set to low. (Default is checked)Channels: 6Positive Edge Clk: UN-CheckedFPGA: Serial 1408 Class. CONFIGURE SOFTWARE SCREENThe software interface is highly configurable and displays any combination of time domain data, fre-quency domain data, primitive wave and perform-ance parameters (SNR, THD, SINAD, etc.). The screen can be broken into multiple panes as shown in Figure 2. Complete documentation on configur-ing PSCOPE can be found in the help file.Click the COLLECT button to begin acquiring data. Complete software documentation is available from the Help menu item, as features may be added peri-odically.HARDWARE SET-UPJUMPERSJP1, JP2 - Select number of channels to convert and Unipolar / Bipolar selection. NCH2, NCH1, NCH0 are set to 111 which selects all six channels. These switches should be left in this position when running Pscope software. UNI/BIP selection applies to all channels. Refer to Figure 4.JP3 –Enable Oscillator and Oscillator Division. Presently not used. This may be used in the future as serial clock, to allow a convert signal at 1X the conversion rate.JP4 – Digital Interface Header. Provides direct con-nection to the LTC2351-14 CONV, SDO, and SCK pins. This can be used to either monitor signals with a logic analyzer or to drive the LTC2351-14 directly from the customer’s test equipment or pro-totype circuitry. DC890B should be disconnected before driving the LTC2351-14 externally with JP4. Note that R34 should be removed if the CONV sig-nal is being driven externally.JP5 – Currently not used SIGNAL CONNECTIONSJ1 –40 pin connector with CH0-CH5 differential inputs, multiple grounds, a mid-supply bias voltage and Vref. Refer to schematic for pin out. The mid-supply bias voltage can be used to bias the minus ADC inputs for bipolar conversions.J2 – Data connections to DC890B collection board. J3– Conversion Clock Input. This input has a 50 ohm termination resistor, and is intended to be driven by a 3.3Vpp sine or square wave. This clock is divided by 98 in the DC890B collection board to control the serial interface and convert pulse. To run the LTC2351-14 at maximum conversion rate, apply a 25MHz signal to this input.GROUNDING AND POWER CONNECTION Connect a 5V to 7V power supply to the Vin and GND turret posts. For optimum performance, this supply should be floating with respect to any signal generators connected to the analog inputs.Figure 4 – JP1, JP2 CONFIGURATION。
SX1278、SX1276的LoRa技术知识详解
SX1278、SX1276的LoRa技术知识讲解
载波频率：
载波频率就是没有调制数据的纯射频信号，用来载送信号的频率，在这个频率的基础上进行移频键控的调制输出无线信号，通常说发射频率就是指载波频率。
扩频因子：
扩频因子是码分多址的基本组成部分，码片速率=符号速率*扩频因子，扩频因子的使用使得TD中的信道的符号速率选择性更大，为业务QOS保证提供了强有力的支持，扩频因子也决定了可接入中端的数量。
扩频因子的大小决定了一个用户的实际数据数率的大小（注意，这里说的是实际数据，例如大家都传输11111111这个数据，A用11表示1，那么他的实际数据是1111，而B用1111表示1，那么他的实际数据为11，这样B的出错概率就比A小，但他的数据数率也比A小）但是因为正交码的存在，从基站上看，提高扩频因子，对某一用户的实际数据数率降低了，但同时的可用用户数多了（扩频码）整体的
实际数据数率却没变。
扩频带宽：扩频带宽，信号在以载波频率为中心频率，在设置的带宽下进行调制。
下图是125K和250K的扩频带宽图（紫线是保持，黄线是调制信号线）。
扩频带宽的设置也取决于晶体精度是否支持，我们推荐最低的扩频带宽是125K。
ADS1278使用总结
1.数据输出格式2.引脚说明3.速度模式设置芯片一共有4种速度模式，下图为4种模式的最大采样率及功耗表：以上四种工作模式用MODE1和MODE0控制，其对应关系如下表，当为High-Speed时，fclk最大可为37MHz，其他三种模式时，最大输入时钟为27MHz。
且当fclk>27MHz时，只能采用Frame-Sync方式读取数据。
在High-Speed模式下，不同的时钟频率(fclk)对DVDD和参考电压（Vref）的的要求也不一样，具体如下表所示：ADS1278的数据输出率与fclk具有固定的比例关系，且Low-Power和Low-Speed模式下，CLKDIV能够对fclk分频。
另外两种模式下，CLKDIV必须为1，具体关系如下表所示：注意：在High-Speed模式下，若为TDM方式输出，因为8个通道均通过OUT1输出且数据为24bits，故必须保证clk=SCLK4.输出方式设置采样数据可通过两种方式输出SPI方式和Frame-Sync方式。
输出方式由FORMAT[2:0]控制，如下图所示。
TDM表示8个通道数据全部由DUOT1输出，CH1在前，CH8在后。
此时若DATA POSITION 为Dynamic则表示：若某通道关闭，则该通道仍然输出，输出数据为0。
若DATA POSITION 为Fixed，则如果某通道关闭，则该通道不输出，直接输出下一通道数据。
5.供电电压ADS1278需要3个电压DVDD、IOVDD和AVDD。
其中DVDD电压为1.65-1.95V（当32.768MHz < f CLK ≤37MHz时，DVDD须为2.0-2.2V）;IOVDD电压为1.65V-3.6V; AVDD电压须为4.75V-5.25V。
且每个电源引脚处均须放置一个10UF钽电容和0.1UF陶瓷电容。
且ADS1278严格要求电源稳定，不可与其它易产生电源峰值的器件共用电源。
●电路设计：DVDD和IOVDD采用TPS730xx系列LDO电源芯片。
ADM1278 Design Guide
AN-1338APPLICATION NOTEOne Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • ADM1278 Design Guideby Paul O’SullivanINTRODUCTIONThe following design guide is intended to be used with theADM1278 Microsoft® Excel®-based design tool, the ADM1278 Hot Swap Designer. The headings in this application note correspond to the numbered headings in the design tool.SYSTEM SPECIFICATIONSEnter the system specifications. For example, critical specifications can be as follows: • V IN = 12 V ± 5% (supply voltage)• I CB = 70 A (circuit breaker trip current) • C LOAD = 3000 µF (total load capacitance) •T A_MAX = 60°C (ambient temperature)UV PIN THRESHOLDAn internal comparator with a 1 V reference detects the UV pinfalling threshold.V 1×+=RUV2RUV2RUV1UV FALLINGwhere:RUV1 is the top resistor in the resistor divider string on the UV pin divider from V IN to ground.RUV2 is the bottom resistor in the resistor divider string on the UV pin divider from V IN to ground.The UV pin has 60 mV of hysteresis, so the rising threshold can also be calculated asUV RISING = UV FALLING + (UV FALLING × 60 mV)A decoupling capacitor can also be added to the UV pin if required. This capacitor extends the glitch filter time of the UV pin.OV PIN THRESHOLDAn internal comparator with a 1 V reference detects the OV pin rising threshold.V 1×+=ROV2ROV2ROV1OV RISINGwhere:ROV1 is the top resistor in the resistor divider string on the OV pin divider from V IN to ground.ROV2 is the bottom resistor in the resistor divider string on the OV pin divider from V IN to ground.The OV pin has 60 mV of hysteresis, so the falling threshold can also be calculated asOV FALLING = OV RISING − (OV RISING × 60 mV)A decoupling capacitor can be added to the OV pin if required. This capacitor extends the glitch filter time of the OV pin.CURRENT LIMIT SETTINGSThe sense voltage (V SENSE ) can be programmed within a 5 mV to 25 mV range using the ISET pin. The range of 15 mV to 25 mV is recommended for optimum accuracy.For example, to configure a regulation current limit (I REG ) of 73 A, the sense resistance (R SENSE ) is calculated asΩ≈==m 0.273A37V020.0REG SENSE SENSE I V R This R SENSE value is not a commonly available resistor, so the closest to consider is 0.25 mΩ (for example, two 0.5 mΩ resistors in parallel).V SENSE = R SENSE × I REG = 0.25 mΩ × 73 ≈ 18.25 mV V ISET = V SENSE × 50 = 18.25 mV × 50 = 0.912 VBecause the VCAP pin has a limited load current specification, the top ISET resistor (RISET1) is kept relatively large, (for example, 10 kΩ to 100 kΩ). The bottom resistor (RISET2) can then be adjusted to provide the required sense voltage limit. The ISET pin can be tied directly to the VCAP pin to configure the default 20 mV current limit. Enter 20 mV as the target V SENSE value to configure the default current limit.Up to four sense resistors can be selected in parallel. A general guideline is to allow a 10% imbalance between resistors. Resistors must also be sufficiently thermally derated. For example, a resistor that is rated for 2 W must not be dissipating more than ~1 W . The TT Electronics ULR3 series of resistors, or equivalent, is recommended. The ULR3 resistor is a 3 W , 2512 case size resistor. See the EV AL-ADM1278EBZ user guide for the recommended sense resistor footprint when using the ULR3 resistors. Averaging resistors are required when using multiple sense resistors. A 10 Ω averaging resistor at each sense resistor terminal is recommended.The minimum, maximum, and nominal circuit breaker current limits and regulation current limit are shown in the tool after the sense resistor and ISET resistor values are populated.AN-1338Application NoteFET SELECTIONGenerally, the maximum current must not exceed approximately 25 A to 30 A per field effect transistor (FET) for a typical power metal-oxide semiconductor field effect transistor (MOSFET) in an LFPAK case size. This guideline gives an indication of the number of FETs that are required.The first consideration as criteria for selection of a suitableMOSFET is the drain source on-resistance (R DSON ) specification. The R DSON value determines how much power is dissipated in the MOSFET when it is fully enhanced in normal operation. The ADM1278 features a high voltage gate drive which generates a minimum gate-to-source voltage (V GS ) of 10 V to achieve the lowest specified R DSON . The gate drive circuit is designed to achieve this gate drive while still ensuring the 20 V maximum V GS specification is not violated.The temperature rise in the MOSFET during normal operation is directly proportional to the R DSON of the MOSFET. This temperature rise impacts the derating factor required tomaintain the safe operating area (SOA) of the MOSFET. As the temperature of the MOSFET increases, its power rating is reduced, or derated. In addition, running MOSFETs at high temperatures may decrease their reliability.Begin by estimating the required R DSON . Check the maximum dc current calculated previously in Section 4 of the design tool (Current Limit Settings). Assume there is a maximum dc current of 75 A for the purposes of these calculations. Then, using the maximum ambient temperature specified in Section 1 (System Specifications), estimate the power loss in the MOSFET(s). First, make the following assumptions: • Junction to ambient thermal resistance of the MOSFET (R THJA ) = 40°C/W (this rating must not be exceeded) •T JMAX = 120°C (this is the maximum preferred MOSFET junction temperature, keeping well below any silicon limits)First, calculate the junction temperature rise.T RISE = T JMAX − T AMAX = 120°C − 60°C = 60°C Then, calculate the power for a single FET.W 5.1C/W 40C 60=°°==THJARISE MOSFET R T PThen, calculate the total R DSON .m 266.0A)75(W 5.122Ω===MAXDCMOSFET DSON I P RThis R DSON value is far too small for a single FET, so calculate it with three FETs in parallel, instead.() m 4.225W 5.13/22Ω===MAXDC MOSFETDSON I P RReduce this R DSON value by 10% to create a margin for imbalance, due to layout asymmetry, and a further 1.4 factor to allow some derating.m 5.14.19.0m 4.2Ω=×Ω=DSON RTaking this R DSON value as the target R DSON , search for suitable FETs. The search can be narrowed to FETs that fit the following profile: • V DS = 25 V to 30 V (20 V is possible, but is not preferred). • V GS = 20 V .• R DSON ≤ 1.4 mΩ.•T JMAX = 175°C (150°C is possible, but 175°C allows for a lower temperature derate factor. This is the silicon limit for the MOSFET. The maximum junction temperature is still targeted at 120°C to avoid thermal runaway).After selecting a suitable MOSFET , quantify the R DSON temperature derate required. There is typically a graph of R DSON vs. T J in the MOSFET data sheet. An example of normalized R DSON vs. T J is shown in Figure 1.12777-001N O R M A L I Z E D R D S O N (m Ω)JUNCTION TEMPERATURE (°C)2.01.51.00.50–60060120180Figure 1. Normalized R DSON vs Junction Temperature (T J )Using a T JMAX of 120°C, the R DSON increases by a factor of approximately 1.4. It is recommended to keep T J ≤ 120°C. After a suitable MOSFET is selected, the remainder of Section 5 (FET Selection) of the design tool can be populated. The threshold voltage (V GS(TH)), the reverse transfer capacitance (C RSS ), and the input capacitance (C ISS ) values can usually be found in the specification table or in the typical performance characteristics of the MOSFET data sheet.Application NoteAN-1338DETERMINE THERMAL POWER DERATING FACTORSThe worst case temperature rise is calculated based on dataentered previously. A derating factor (DF) of approximately 2 or less is recommended to avoid thermal runaway.CMAXJMAX CSOA JMAX T T T T DF −−=where:T CSOA is the SOA case temperature (for example, 25°C). T CMAX is the case temperature at T JMAX .V OUT RAMP TIMEThe gate capacitor (C GATE ) limits the inrush current and allows the output voltage to come up in a linear ramp. The capacitor must be large enough to ensure that the inrush current is low enough to not trip the circuit breaker threshold. Start with a 10 nF capacitor and increase its value until the inrush current is low enough and the tool no longer gives a warning. Typical values for the gate capacitor are 22 nF or 33 nF .The gate capacitor value can also be chosen to give a desired power-up ramp time. For example, to configure a power-up ramp of 20 ms,()FET PER RSS IN GATEUPGATE CNumFETs V I t C __×−×= where:t UP = 20 ms power-up ramp time. I GATE = 25 µA.V IN = nominal supply voltage.NumFETs is the number of MOSFETs.C RSS_PER_FET is the reverse transfer capacitance per FET. Round up the gate capacitor to the nearest available value.SOACopy the chosen MOSFET SOA into the FET SOA tab of the design tool. It is recommended to use the 1 ms SOA time for the calculations because SOA times are not easy to predict in between the characterized times on the SOA plot. Fill out the SOA values in the table for Section 8 of the FET SOA tab to allow the tool to calculate the maximum allowable power for each SOA time.PSETThe ADM1278 utilizes a constant power foldback technique to protect the MOSFETs in the event of overcurrent faults or short circuits. The V DS of the MOSFET is monitored. The current limit is adjusted based on the V DS of the MOSFET to maintain a constant power limit. See Figure 2 for an example of this relationship.12777-002F E T C U R R E N T (A ) A N D P O W E R (W )FET V DS (V)50024********Figure 2. Constant PowerThe ADM1278 design tool calculates the maximum constant power value to ensure that the MOSFET SOA is maintained. It also calculates the minimum constant power value to ensure that the constant power threshold is not tripped at power-up. Choose the power limit somewhere close to the center of this range to allow margin at each side. The typical value for the FET power limit in a design is 250 W .After the FET power limit is chosen, the PSET resistor divider from the VCAP pin to ground can be selected to give the required PSET voltage. The MOSFET SOA must be checked at the constant power setting selected. Click on the link in Section 9 of the FET SOA tab and enter the approximate SOA time at the derated constant power level. Check the design worksheet for any SOA warnings. The SOA time at this constant power level must be larger than the selected maximum SOA time (for example, the 1 ms SOA line that was recommended).ISTARTThe start-up current limit is a fixed current limit that is only active when PWRGD is bad (the PWRGD pin deasserted). Thiscurrent limit can therefore detect any unexpectedly large inrush current during dv/dt power-up. During dv/dt power-up, the inrush current is typically less than the active current limit determined by the ISET pin or constant power foldback.AN-1338Application NoteThe ISTART pin is used to select the start-up current limit. It can be tied high to disable the start-up current limit, tied low for a default V SENSE limit of 2 mV , or it can be configured with a resistor divider to the VCAP pin to configure a specific current limit.VCAP R R R V ISTART2ISTART1ISTART2ISTART ⨯+=where:R ISTART1 is the top resistor in the resistor divider string on the ISTART pin from the VCAP pin to ground.R ISTART2 is the bottom resistor in the resistor divider string on the ISTART pin from the VCAP pin to ground.SENSECSAMP ISTARTR AV V StartupCL ⨯=where:StartupCL is the start-up current limit at initial power-up. A V CSAMP = 50 V/V (gain of current sense amplifier).The start-up current limit must be greater than the maximum expected inrush current to ensure that the circuit breaker threshold is not tripped during a normal dv/dt power-up ramp. The start-up current-limit threshold is typically set in between the maximum expected inrush current and the minimum constant power current limit. If the maximum expected inrush current is 5 A, the start-up current limit is typically set to approximately 10 A. After a start-up current limit is selected, the ISTART resistor divider on the VCAP pin can be configured in the ADM1278 design tool.It is also possible to program the start-up current limit via the PMBus interface. See the ADM1278 data sheet for more details.MOSFET SOA ANALYSIS AT POWER-UPOne final MOSFET SOA check is required for the worst case FET power at power-up. The MOSFET SOA time for a power-up ramp is estimated in Section 10 of the FET SOA tab. After entering the appropriate time, check the design worksheet again for any warnings. The SOA time must be larger than the maximum power-up time that was calculated. TIMERThe TIMER pin capacitor (C TIMER ) is used for fault protection. When the ADM1278 is configured to power up in a linear ramp, the TIMER pin threshold is normally tripped only during a fault condition. As such, the regulation period of the TIMER pin can be considered as a glitch filter time for fault conditions. For high current designs, it is recommended to set this fault filter time to approximately 100 μs to 500 μs duration. A C TIMER capacitor value of 10 nF to 22 nF is recommended.PWGIN PINThe PWRGD pin is an open-drain output pin and is pulled low in the following cases: ∙ There is a fault condition that has not been cleared∙ The controller has not signaled that the hot swap can be enabled∙The power-good input threshold has not been exceededThe PWRGD falling threshold is set by a resistor divider on the PWGIN pin.V 1⨯+=RPWGIN2RPWGIN2RPWGIN1PWGIN FALLINGwhereRPWGIN1 is the top resistor in the resistor divider string on the PWGIN pin divider from V OUT to ground.RPWGIN2 is the bottom resistor in the resistor divider string on the PWGIN pin divider from V OUT to ground. The PWGIN pin has 60 mV of hysteresis, so the rising threshold can also be calculated asPWGIN RISING = PWGIN FALLING + (PWGIN FALLING × 60 mV)RECOMMENDED CIRCUITAssuming there are no warnings, the design is complete. Click on the link in the design tool to go to the tab with the schematic and the bill of materials that is generated from the design.©2014 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.AN12777-0-12/14(0)。
ADS1278使用总结
ADS1278使用总结ADS1278是一种高精度、低功耗的模数转换器，具有8通道的输入通道，适用于各种工业和医疗设备的应用。
本文对ADS1278的使用进行总结，包括其特点、应用、性能评价和使用注意事项等方面的内容，旨在为用户提供有关ADS1278的详细信息。
首先，我们来介绍一下ADS1278的主要特点。
ADS1278具有12位的分辨率，可提供高达20位的有效分辨率。
它采用了Delta-Sigma架构，具有低噪声、低失真和高线性度的特点。
此外，ADS1278具有内部可编程增益放大器和数字滤波器，可提供灵活的配置选项，以适应不同的应用需求。
ADS1278适用于各种应用场景。
对于工业自动化领域来说，ADS1278可用于处理各种传感器信号，如温度、压力、位置等。
在医疗设备领域，它可用于心电图仪、血压监测仪等设备中，提供高精度的生理信号采集。
此外，ADS1278还可以应用于音频设备和通信设备等领域，提供高质量的音频信号采集和处理。
接下来，我们将对ADS1278的性能进行评价。
首先是分辨率和动态范围。
ADS1278具有12位的分辨率，能够提供高达20位的有效分辨率，能够准确地采集和处理微小的信号变化。
其次是采样率和带宽。
ADS1278的最大采样率为105kSPS，可以满足大多数应用的需求。
其带宽范围为DC至5kHz，在音频采集方面具有良好的性能。
在使用ADS1278时，需要注意以下几个方面。
首先是参考电压的选择。
通过外部引脚，可以设置ADS1278的参考电压，以适应不同的输入信号范围。
其次是时钟信号的输入。
ADS1278通过外部引脚接收时钟信号，需要确保时钟信号的稳定性和精确性，以保证采样的准确性。
另外，还需要注意电源和地线的布局，以减小噪声的影响，提高采样精度。
综上所述，ADS1278是一种功能强大的模数转换器，具有高精度、低功耗等特点。
它适用于各种工业和医疗设备的应用，能够提供高质量的信号采集和处理。
在使用ADS1278时，需要注意参考电压、时钟信号、电源和地线等方面的问题，以确保采样的准确性和性能的稳定性。
ADS1274使用要点
1、引脚连接有典型接法。
2、SPI模式最大CLK27M、FSYNC模式最大37M。
3、DRDY/FSYNC,不同的模式输入输出不同。
SPI模式DRDY输出，FSYNC模式FSYNC输入控制。
4、PWDN5-8，必须接地。
5、供电顺序，有些影响但是没有那么大。
AVDD、IOVDD、DVDD，不同的模式，使用的电压不同，有图表。
6、IOVDD、DVDD可以连接在一起，但是要满足IOVDD电压。
IOVDD电压是数字引脚识别电压。
7、FORMAT设置工作模式，SPI、FSYNC，，，，定点、随机，，，，TDM。
有图表。
8、SYNC信号设置四路之间同步采集。
9、PWDN信号可以停用相应的通道，figure75图时序。
10、输入范围Vin=AINP-AINN。
- VREF到+VREF,这里的正负不是可以输入负电压，而是AINP-AINN可以为负（差分输入）。
任何AD的输入电压范围都不能超过供电电压范围。
11、MODE设置速度、精度模式。
每种模式都有其最大工作频率。
12、DIN用于链模式，TEST用于检测引脚之间的联通，有图表。
13、CLKDIV高低电平不同，接受的最大频率不同。
14、（SPI模式，FSYNC模式不知道）CLK控制采集电压的频率，SCLK控制读取数据的频率15、FSYNC模式，采集数据的频率和CLK满足256-2560的关系。
16、SPI模式：DRDY下降沿后，最高位（符号标志位即是输出到DATA上），SCLK出现在DRDY低电平期间第一个上升沿数据即被读取。
但是在SCLK必须在DRDY低电平期间的第一个由上升沿变换到下降沿，DRDY才变高。
（和时序图不太一样）17、最大的参考电压并不大一般是-2.5V---2.5V经验：1)时钟分为CLK、。
SCLK决定每1bit数据的传输速率，即每一个时钟传输1bit数据。
CLK的数值除以256-2560（参考DIVCLK,和FORMAT设置工作模式选择256-2560数值）是采样率的设置。
基于ADS1278的高精度采样平台的搭建
１ ． ２ Ｔ ＭＳ ３ ２ ０ Ｆ ２ ８ ３ ３ ５ 简介 １ Ｍｓ ３ ２ Ｏ Ｆ ２ ８ ３ ３ ５ 是１ ｆ Ｉ 公司针对要求严格的控制应用而 提出的高度集成、高性能解决方案 。它采用高性能的静态
Ｃ ＭＯ Ｓ技术 ，指 令周 期为 ６ ． ６ ７ ｎ ｓ ，主频 达 １ ５ ０ ＭＨ ｚ ；高 性 能的 ３ ２ 位 Ｃ Ｐ Ｕ，单精度浮点运算单元 （ Ｆ Ｐ ｕ） ，采用哈佛 流水线结构，能够快速执行 中断响应 ，并具有统一的内存
３ 接 口电路 设计
图 １基于 Ａ Ｄ Ｓ １ ２ ７ ８的高精 度数 据采 集系 统框 图 ３ ． １ 基本 差分 输入 信 号接 口电路 １ ． １ Ａ ＤＳ １ ２ ７ ８ 简 介 基 本 差分输 入信 号接 口电路采 用 Ｏ Ｐ Ａ１ ６ ３ ２ 和 旁路 电容 Ａ Ｄ Ｓ １ ２ ７ ８ 是德州 仪器 （ ， Ⅱ ） 推 出的 多通道 ２ ４ 位工 业模 数 构成 ，ＯＰ Ａ１ ６ ３ ２是 一款 可 以驱 动高 性能 模数 转换器 的全 差 转换器，可实现 ８通道同步采样，支持高速、高精度、低 分放大器【 ５ 】 。Ｏ Ｐ Ａ ｌ ６ ３ ２ 采用正负 １ ０ Ｖ双电源供 电，能够满 功耗、 低速 ４种工作模式； Ａ Ｄ Ｓ １ ２ ７ ８ 具有优 良的Ａ Ｃ和 Ｄ Ｃ 足 系 统要 求 ，又 可 以极大 的 降低运 算放 大 器 的功耗 。运 算 特性，采样率最高可 以达 １ ２ ８ Ｋ ｓ ／ Ｓ ，６ ２ ｋ Ｈ ｚ 带宽时信噪 比 放大器构成的接 口电路如图 ２所示。Ａ Ｄ Ｓ １ ２ ７ ８的 Ｃ Ｏ Ｍ 端 （ Ｓ Ｎ Ｒ ） 可达 １ １ ｌ ｄ Ｂ ，失 调漂移 为 ０ ． ８ １ ａ Ｖ／℃。 【 ｌ Ｊ Ｉ ｚ Ｊ Ａ Ｄ Ｓ １ ２ ７ ８ 输 出经 过 电压跟 随器 后连接 到 Ｏ Ｐ Ａ１ ６ ３ ２的 Ｃ Ｏ Ｍ 端 ，用 于
基于ADS1278的高精度采样平台的搭建
基于ADS1278的高精度采样平台的搭建摘要：介绍了一种基于ti公司的模数转换器ads1278和tms320f28335型dsp构成的高精度采样平台，完成了dsp和模数转换器的接口电路及控制电路设计，具有多通道同步采样，高精度，低功耗等特点。
关键词：ads1278；高精度；数据采集；tms320f28335中图分类号：tp274 文献标识码：a 文章编号：1007-9599 （2013） 03-0000-03数据采集技术已广泛应用于信号处理、通信、过程控制、遥感遥测等领域，在这里我们介绍一种基于tms320f28335和ads1278的高精度数据采集系统。
它能够实现多通道同步采样以及高精度。
1 模块总体介绍和系统框架1.2 tms320f28335简介2 控制电路设计3 接口电路设计3.1 基本差分输入信号接口电路基本差分输入信号接口电路采用opa1632和旁路电容构成，opa1632是一款可以驱动高性能模数转换器的全差分放大器[5]。
opa1632采用正负10v双电源供电，能够满足系统要求，又可以极大的降低运算放大器的功耗。
运算放大器构成的接口电路如图2所示。
ads1278的com端输出经过电压跟随器后连接到opa1632的com端，用于提供差分输入信号参考电压。
3.2 参考源设计3.3 tms320f28335与ads1278的接口电路ads1278帧同步串行接口有sclk，fsync，dout和clk时钟，一共有4个接口。
tms320f28335的多通道缓冲串口（mcbsp）支持帧同步串行通信模式与spi模式。
在这里，我们采用帧同步格式来接收数据。
mcbsp共有6路信号，其中包括时钟信号通路clkx和clkr，数据传输信号通路dx和dr以及帧同步信号通路fsx和fsr。
我们仅需使用clkr、fsr和dr即可完成数据的接收。
将dsp的clkr连接到ads1278的sclk和clkk，fsr连接到fsync引脚，dr连接到dout1。
ADS1278使用总结
1.数据输出格式2.引脚说明3.速度模式设置芯片一共有4种速度模式，下图为4种模式的最大采样率及功耗表:以上四种工作模式用MODE1和MODE0控制，其对应关系如下表，当为High—Speed 时，fclk最大可为37MHz,其他三种模式时，最大输入时钟为27MHz。
且当fclk〉27MHz 时，只能采用Frame—Sync方式读取数据。
在High-Speed模式下,不同的时钟频率(fclk)对DVDD和参考电压（Vref）的的要求也不一样，具体如下表所示:ADS1278的数据输出率与fclk具有固定的比例关系，且Low—Power和Low—Speed模式下，CLKDIV能够对fclk分频.另外两种模式下，CLKDIV必须为1,具体关系如下表所示：注意：在High—Speed模式下，若为TDM方式输出，因为8个通道均通过OUT1输出且数据为24bits，故必须保证clk=SCLK4.输出方式设置采样数据可通过两种方式输出SPI方式和Frame-Sync方式.输出方式由FORMAT[2：0］控制，如下图所示。
TDM表示8个通道数据全部由DUOT1输出，CH1在前，CH8在后。
此时若DATA POSITION 为Dynamic则表示：若某通道关闭,则该通道仍然输出,输出数据为0。
若DATA POSITION 为Fixed，则如果某通道关闭，则该通道不输出,直接输出下一通道数据。
5.供电电压ADS1278需要3个电压DVDD、IOVDD和AVDD。
其中DVDD电压为1.65-1.95V（当32.768MHz 〈f CLK ≤37MHz时，DVDD须为2.0-2.2V）；IOVDD电压为1。
65V—3.6V；AVDD电压须为4.75V-5.25V。
且每个电源引脚处均须放置一个10UF钽电容和0。
1UF 陶瓷电容。
且ADS1278严格要求电源稳定，不可与其它易产生电源峰值的器件共用电源。
●电路设计:DVDD和IOVDD采用TPS730xx系列LDO电源芯片。
SX1278data中文手册带书签
SX1278data中文手册带书签一、产品简介SX1278是一款高性能、低功耗的射频收发器，广泛应用于远程无线通信领域。
本手册旨在帮助用户了解SX1278的功能特点、电气特性、封装类型及使用方法，方便用户快速上手并充分发挥其性能。
二、功能特点1. 工作频率范围：137525MHz2. 可编程传输速率：0.018bps 300kbps3. 高灵敏度：低至148dBm4. 高线性输出功率：最高达+20dBm5. 支持多种调制方式：FSK、GFSK、OOK、4FSK、MSK等6. 内置温度传感器和低电压检测功能7. 小尺寸封装：QFN243mm×3mm三、电气特性1. 工作电压：1.83.7V2. 接收电流：10mA（典型值）3. 发送电流：100mA（典型值，+20dBm输出功率）4. 睡眠电流：≤200nA5. 待机电流：≤2.5μA四、封装类型1. GND：地2. VCC：电源正极3. ANT：天线接口4. SCLK：时钟信号输入5. MISO：数据输出6. MOSI：数据输入7. NSS：芯片选择8. NRESET：复位信号9. DIO0DIO5：数字IO口，可配置为中断输出或其他功能10. RXTX：收发控制信号11. BOOT：启动模式选择12. LDIO：低压检测输出13. TEMP：温度传感器输出五、使用方法1.硬件连接（1）将SX1278的GND、VCC、ANT分别连接到电路板的相应位置。
（2）将SCLK、MISO、MOSI、NSS、NRESET、DIO0DIO5、RXTX、BOOT、LDIO、TEMP等引脚按照实际需求连接到单片机或其他控制器。
2.软件配置（1）通过SPI接口向SX1278写入配置参数，包括工作频率、波特率、调制方式等。
（2）配置DIO0DIO5等引脚的功能，如设置为中断输出。
（3）根据实际需求，编写发送和接收程序。
3.发送数据（1）设置SX1278为发送模式。
24位高性能模数转换器ADS1274_ADS1278及其应用
６ 结束语
ＡＤＳ１２７４／１２７８ 是基于 Δ－ Σ技术的 ２４ 位高性 能工业模数转换器，内部集成有多个独立的高阶斩 波稳定调制器和 ＦＩＲ 数字滤波器，具有优良的 ＡＣ 和 ＤＣ 性能，可实现 ４／８ 通道同步采样，支持高速、 高精度、低功耗、低速 ４ 种工作模式；数据输出可选 帧同步或 ＳＰＩ 串行接口，每个接口均支持菊花链连 接，可应用于要求严格的多通道信号采集系统，如 振动分析、医疗监控、动态应变测量设备等。 参考文献： ［１］ Ｔｅｘａｓ Ｉｎｓｔｒｕｍｅｎｔｓ Ｉｎｃｏｒｐｏｒａｔｅｄ． ＡＤＳ１２７４／ＡＤＳ－
２４位高性能模数转换器 ＡＤＳ１２７４／ＡＤＳ１２７８ 及其应用
王怀秀 １， ２， 朱国维 ２
（１． 北京建筑工程学院，北京 １０００４４；２． 中国矿业大学（北京）煤炭资源教育部重点实验室，北京 １０００８３）
摘要：介绍了是德州仪器的多通道 ２４ 位工业模数转换器 ＡＤＳ１２７４／ＡＤＳ１２７８ 的性能特点、引脚功
监控、声学／动态应变测量及压力测量设备等。
２ 性能特点
传统的具有较高漂移性能的工业 Δ－ ΣＡＤＣ 采 用导通带宽滑落幅度很大的数字滤波器，来得尽可 能满足 ＤＣ 测量需求的有限信号带宽。针对音频应 用的高分辨率 ＡＤＣ 能够提供更大的可用带宽，但 偏 移 与 漂 移 规 范 远 低 于 工 业 ＡＤＣ。 ＡＤＳ１２７４／ ＡＤＳ１２７８ 将两种类型的转换器相结合，实现最佳 ＤＣ 与 ＡＣ 规范的高精度工业测量。具体特点如下：
图 ２ ＴＤＭ 模式，固定位置数据（通道 １ 和通道 ３ 为掉电状态）输出
－ ５６－
《国外电子元器件》２００８ 年第 ５ 期 ２００８ 年 ５ 月
基于ADS1271的激光功率密度检测系统的设计
在激光医疗领域 ，激光的功率密度能够很好 的反映出对患病部位治疗剂量等信息也是影响医用弱激光
和Ｐ Ｄ Ｔ（ Ｐ ｈ ｏ ｔ ｏ ｄ ｙ ｎ ａ ｍ ｉ ｃ Ｔ ｈ ｅ ｒ ａ ｐ ｙ ，光动力疗法 ） 治疗疗效的主要因素 ，因此 ，快速 、准确的测量出激光功率
因此由式 （ ２ ） 、 （ ３ ） 、（ ４ ） 联合可得激光的功率与传感器温度有如下关 系
户 （ ｒ ） ＝ 硎
根据式 （ １ ） 、（ ５ ）联合 可得 ，激 光 功率 与热 电偶 传感 器输 出 电压关 系为
Ｐ （ ｆ ） ＝ ｋ Ｅ （ ｔ ）
２ ． ２ 量程选 择 电路
量程 选择 电路其实 质是 以
其 中， 为串联有效热电偶数 目， 为塞贝克系数。因此 ， 输 出电势与被测辐射所产生的温度差呈正 比例 函数关系。 激光辐射传感器的能量以内能的形式储存在传感器中，随着 内能的增加传感器的温度也会随之上升，
因此 内能与 温度有 如下关 系
Ｑ （ ｆ ） ＝ ｃ ｍ Ｔ （ ｔ ）
１ 总体结构设计
本系统主要由信号采集模块 、信号转换模块和
信号处 理模块 三部 分组 成 ，其结 构 如 图 １ 所示 。
信 号采集模块主要 由热 电堆传感器和量程转 换 电路组成。热电堆传感器用于采集激光平均功率 信号 ；量程转换电路选择可以合适测量量程 ， 使用
信号 转 换模块 — — —
参数设定 、数据处理和结果显示 。
２ 信号采集模块设 计
ads1258用法 -回复
ads1258用法-回复ads1258是一种高精度、低噪声模数转换器（ADC），用于测量模拟信号并将其转化为数字信号。
在本文中，我们将详细介绍ads1258的用法，并逐步回答一些常见问题。
第一步，我们将从ads1258的基本特性开始。
ads1258是一款16位ADC，具有24位的有效分辨率，采样率高达30 kHz。
它具有低输入偏差电流和低输入噪声的特点，使其成为高精度测量的理想选择。
第二步，我们需要了解ads1258的硬件连接。
ads1258具有多个引脚，包括数据输入、模拟输入、时钟输入等。
我们需要确保正确连接这些引脚以实现正确的功能。
例如，我们可以将模拟输入引脚连接到要测量的信号源，数据输出引脚连接到控制器或处理器等。
第三步，我们需要配置ads1258的寄存器以实现所需的测量参数。
ads1258具有多个寄存器，用于配置不同的参数，例如增益、采样率和工作模式等。
我们可以使用特定的命令或寄存器配置工具来设置这些参数。
确保根据实际需求进行正确配置。
第四步，我们可以开始进行实际的模拟信号转换。
启动ads1258后，它会根据配置的参数开始进行模拟信号测量。
adc将模拟信号转换为数字信号，并将其输出到数据输出引脚。
我们可以使用控制器或处理器读取这些数字数据并进行进一步的处理或分析。
第五步，我们还需要注意ads1258的基准和校准。
ads1258的性能可能会随时间和环境的变化而发生变化。
因此，我们需要定期进行校准以确保精确的测量。
校准可以通过将已知电压应用于模拟引脚并与读取的数字值进行比较来完成。
根据比较结果，我们可以调整ads1258的参数或进行其他校准操作。
除了基础用法外，ads1258还具有其他一些高级功能和应用。
例如，它支持不同的工作模式，如连续转换模式和单次转换模式。
它还可以通过配置外部时钟源来提供更高的采样率。
对于特殊应用，ads1258还可以与其他传感器或模块进行接口，以实现更复杂的测量任务。
ADS1198ADS1298开发设计心得与遗留问题总结
ADS1198/ADS1298开发设计心得与遗留问题总结首先非常感谢TI公司的支持，自己手里面的6片ADS1198全部是从TI公司申请到的，并且遇到问题后能TI的技术支持工程师能及时给出解答，所以写这篇文章，一是对自己这几个月工作的总结，二是也算是对TI 公司的感谢，也希望能帮助到以后使用ADS1198/1298的朋友。
本人使用MSP430F5418与ADS1198设计12导心电监测仪，其实就是个低档的HOLTER,在HOLTER的基础上加了几个操作按键和LCD显示屏。
历时3个多月，前几天算是能比较满意的用ADS1198采集到ECG信号了！现在简单说下开发过程以及遇到的一些问题。
先说下MSP430单片机，本人01年开始使用（那是还是大四），先后使用过1100,135,149,2418等型号，这次选用了5418，因为信价比高，等开始实际调试使用时，才发现5418与之前的型号有很多升级。
增加了几个功能模块同时也整合了一些功能模块。
比如SYS模块,PMM模块，UCS模块等（还有一些功能由于没用上也没研究），这几个模块我看了很长时间英文资料（英文水平不咋地）后，发现SYS和PMM模块对我根本就没有用，并且把PMM模块关掉了，增加了这些模块视乎能提高430的安全性，但我觉得430这种单片机由于设计宗旨是低功耗3V供电。
所以一般都是采用电池供电的，加上这2个模块似乎意义不大。
反而与之前的型号兼容性不好了！本人在做这款12导心电监测仪之前搞过1年多心电，只用运放做过9导心电监测仪，所以在ECG方面的经验还是很少的，发现这款ADS1198芯片还是在电源网上看到的，申请到样片后，手册和开发指南看了不下七八遍才基本理解明白，现在说说自己曾经迷糊而后来解决以及仍没解决的问题列出来：1.ADS1198有16位AD，可是PGA增益最大只有12，没有二级放大，对于ECG信号最大幅值在5mV左右，经过12倍放大为60MV, 60/2400*65536=1638,即只要用12位就能标示出ECG信号了，也就是说浪费掉了4位AD，如果用ADS1298也会同样出现这种情况，只是会比1198精确些而已，如果用ADS1198/1298测量EEG信号，EEG信号是uV级的，真不能能不能用啊！2.请看手册第12页，这里的这幅图下面的NOTE写着SPI CPOL=0，CPHA=1，但是实际在调试程序时我发现这里应该设置为CKPH=0，CKPL=0.3.手册20页的公共点参考电压的公式似乎也由点问题，这里是A VDD-0.2V我觉得不对，应该是VREF+,因为如果按以上公式计算出的公共参考电压，有可能最大幅值超过VREF+,也就是AD不能正确的采集出实际数值。
ADS1271
proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could101001k10k100kFrequency(Hz)High−Resolution ModeShorted Input1,048,576Points101001k10k100kFrequency(Hz)PACKAGING INFORMATIONOrderable Device Status (1)Package Type Package Drawing Pins Package Qty Eco Plan (2)Lead/Ball FinishMSL Peak Temp (3)ADS1271IPW ACTIVE TSSOP PW 1694None CU Level-2-240C-1YEAR ADS1271IPWRACTIVETSSOPPW162500NoneCULevel-2-240C-1YEAR(1)The marketing status values are defined as follows:ACTIVE:Product device recommended for new designs.LIFEBUY:TI has announced that the device will be discontinued,and a lifetime-buy period is in effect.NRND:Not recommended for new designs.Device is in production to support existing customers,but TI does not recommend using this part in a new design.PREVIEW:Device has been announced but is not in production.Samples may or may not be available.OBSOLETE:TI has discontinued the production of the device.(2)Eco Plan -May not be currently available -please check /productcontent for the latest availability information and additional product content details.None:Not yet available Lead (Pb-Free).Pb-Free (RoHS):TI's terms "Lead-Free"or "Pb-Free"mean semiconductor products that are compatible with the current RoHS requirements for all 6substances,including the requirement that lead not exceed 0.1%by weight in homogeneous materials.Where designed to be soldered at high temperatures,TI Pb-Free products are suitable for use in specified lead-free processes.Green (RoHS &no Sb/Br):TI defines "Green"to mean "Pb-Free"and in addition,uses package materials that do not contain halogens,including bromine (Br)or antimony (Sb)above 0.1%of total product weight.(3)MSL,Peak Temp.--The Moisture Sensitivity Level rating according to the JEDECindustry standard classifications,and peak solder temperature.Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.TI bases its knowledge and belief on information provided by third parties,and makes no representation or warranty as to the accuracy of such information.Efforts are underway to better integrate information from third parties.TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemicalanalysis on incoming materials and chemicals.TI and TI suppliers consider certain information to be proprietary,and thus CAS numbers and other limited information may not be available for release.In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s)at issue in this document sold by TI to Customer on an annual basis.PACKAGE OPTION ADDENDUM27-Dec-2004Addendum-Page 1IMPORTANT NOTICETexas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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全差分伪差分单端输入ADC理解
伪差分：伪差分信号连接方式减小了噪声，并允许在仪器放大器的共模电压范围内与浮动信号连接.在伪差分模式下，信号与输入的正端连接，信号的参考地与输入的负端连接。
伪差分输入减小了信号源与设备的参考地电位(地环流)不同所造成的影响，这提高了测量的精度。
伪差分输入与差分输入在减小地环流和噪声方面是非常相似的，不同的方面在于，差分输入模式下，负端输入是随时间变化的，而在伪差分模式下，负端输入一定仅仅是一个参考。
描述伪差分的另外一种方式就是，输入仅仅在打破地的环流这个意义上是差分的，而参考信号(负端输入)不是作为传递信号的，而仅仅是为信号(正端输入)提供一个直流参考点。
全差分与单端输入：在单端方式工作时；ADC转换的是单输入引脚对地的电压值；在增益为1时，测量的值就是输入的电压值；范围是0V到VREF；当增益增加时，输入的范围要相应的减小；在差分方式工作时；ADC转换的是AIN+与AIN-两个引脚的差值；在增益为1时，测量的值等于(AIN+)-(AIN-)，范围是-VREF到+VREF；当增益增加时，输入的范围要相应的减小。
注意：在差分方式时所提的负压是指AIN-引脚的电压大于AIN+引脚的电压，实际输入到两个引脚的电压对地都必需是正的；例如:如果AIN+引脚输入的电压为0V，AIN-引脚的输入电压为1/2VREF时，差分的输入电压为(0V-1/2VREF) = -1/2VREF。
ADI公司目前针对10KHz左右采样速率的24位ADC推荐AD719X系列的产品。
AD779X属于老产品，老产品噪声较大。
对于单端输入，能测量双极性信号的ADC，内部原理为基准源分压方式，对于TI的MSP430F1161，基准源可提供正负方式。
对于ADuC845的AD输入配置，可以配置为4个全差分输入，或者8个伪差分输入，对于伪差分输入，AINCOM端为参考端。
GAIN越大，ADC的有效分辨率越小，采样速率越高，有效分辨率也越小。
上图参数可得出，全差分的每个输入端口电压不能低于0V，也不能高于规定的电压值。