MAX31865_cn.pdf

该文档是max31865官网上的规格书，便于参考使用此芯片。MAX31865RTD至数字输出转换器Electrical Characteristics (continued)(30V≤VD≤3.6V,TA=40°cto+125°c, unless otherwise noted. Typical values are TA=+25°C,Vp=Vp∨DD=3.3V.)( Notes2and 3)PARAMETERSYMBOLCONDITIONSMINTYP MAX UNITSADC Common -Mode Input0RangeRTD|N+,RTDN-,0°Cto+70°C, on -stateInput Leakage CurrentRTDN-, RTDIN-,40°Cto+85°C,On- stateRTD|N+,RTDN-,-40°Cto100°C,on- stete14Bias voltageVBIAS1.952.002.06Bias voltage Output CurrentOUT0.2575mBias Voltage Load RegulationoUT≤575mA30V/mABias Voltage Startup TimeJote 410msADC Full-Scale errorLSBADC Integral NonlinearityDifferential Input, endpoint fit, 0.3 X VBIAS±1LSB≤VREF≤VBAsADC Offset Error+3LSBNoise(over Nyquist Bandwidth)Input referred150V RMSCommcn -Mode RejectiondB50/60H7 Noise RejectionFundamental and harmonics82dBContinuous conversion(60Hz notch)16.717.6Temperature Conversion TimeSingle conversion(60Hz notch)(Note 5)tcoNVmsSingle conversion(50Hz notch)62.566ontinuous conversion (50Hz notch)2021Automatic Fault Detection CycleTimeFrom Cs high to cycle complete600Power-Supply RejectionLSBAPower-Supply Current(Note 6) Shutdown /Blas off, ADC off1.5mAIDD Bias on, active conversion23.5mAPower-On Reset Voltage2.27ThresholdPower-On Reset Voltage120mvHysteresisInput CapacitanceNLogic inputspFInput leakage currentLogic inputs+1Output High VoltageUT=-1.6mAVDVOH0.4Output Low VoltagelOUT =1.6mA0.4www.maximintegrated.com/cn3MAX31865RTD至数字输出转换器AC Electrical Characteristics: SPl Interface(3.OV VDD <3.6V, TA=-40C to +125C, unless otherwise noted. Typical values are TA=+25 C, VDD Vdvdd=3.3V )(Notes 3and 7)(Figure 1 and Figure 2)PARAMETERSYMBOLCONDITIONSMIN TYP MAX UNITSData to SCLK SetuptDC (Notes 8, 9)sclK to Data hold(Notes 8, 9)SCLK to Data∨alidCDDNotes 8,9,10)SCLK LOW TimetcL (Note 9)100SCLK High TimetcH(Note 9)100SCLK FrequencyCLKNote gDC50MHZSCLK Rise and FalltF(Note 9)200Cs to SCLK Setuptcc ( Note 9)400nsSCLK to CS HoldNote 9100CS Inactive TimeWH (Note 9)400CS to Output high -Z(Notes 8, 9)40Address 01h cr 02h Decoded toDRDY HightDRDYH After RTD register read access(Note 9)50Note 2: All voltages are referenced to ground when common. Currents entering the Ic are specified positiveNote 3: Limits are 100% production tested at TA=+25C and/or TA=+85C Limits over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization. Typical values are not guaranteedNote 4: For 15-bit settling, a wait of at least 10.5 time constants of the input RC network is required. Max startup time is calculatedwith a 10ks2 reference resistor and a 0. 1uF capacitor across the RTD inputsNote 5: The first conversion after enabling continuous conversion mode takes a time equal to the single conversion time for therespective notch trequencyNote 6: Specified with no load on the bias pin as the sum of analog and digital currents. No active communication. If the RtDinput voltage is greater than the input reference voltage, then an additional 400HA lDp can be expectedNote 7: All timing specifications are guaranteed by designNote 8: Measured at VIH-0 7V X VDyDD or VIL -0 3X VDVdd and 10ms maximum rise and fall timesNote 9: Measured with 50pF loadNote 10: Measured at VoH =0.7X VDyDD or VoL =0.3X VDVDD Measured from the 50% point of sclK to the VoH minimum ofSDOwww.maximintegrated.com/cnMAX31865RTD至数字输出转换器DEWRITE ADDRESS BYTEREAD DATA BYTENOTE: SCLK CAN BE EITHER POLARITY TIMING SHOWN FOR CPOL=1图1.时序图:SP读数据传输tccRSCLKtcoWRITE ADDFESS BYTEWRITE DATA BYTElOTE: SCLK CAN BE EITHER POLARITY TIMING SHOWN FOR CPOL=1图2.时序图:SP写数据传输www.maximintegrated.com/cnMAX31856高精度、带线性补偿的热电偶数字转换器典型工作特性(VDD= VDVDD=3.3V, TA=+25C, unless otherwise noted.SUPPLY CURRENT VS, TEMPERATURESUPPLY CURRENT VS TEMPERATURE(ADC AUTO CONVERSION MODE(ADC NORMALLY OFF MODE)ANALOG lou(BIAS PIN UNLOADED)ANALOG IDDi BIAS PIN UNLOADED)IGITAL IDIDIGITAL IDI0EMPERATURELEAKAGE CURRENT PER PIN VS, TEMPERATURESINC FILTER OPERATION(1 VOLT APPLIED TO FORCE+, FORCE2, RTDIN+, RTDIN-PINS)INPUT FREQUENCY VS NOISE RESPONSE14060HZ三80-4C40150170TEMPERATURE(CPUT NOISE FREQUENCYADC CONVERSION ERROR VS RTD RESISTANCEADC CONVERSION ERROR VS RTD RESISTANCE(4k2 RREF, 4-WIRE CONNECTION)04880.4 (4002 BREF, 4-WIRE CONNEC os0.24440°C024425°040°C±01°0C±0.10ERRORERROR+100°0+100°C02440244048804380500100015002000250030003500050100150200250300350RRT(S2)RRTD(S2)www.maximintegrated.com/cn6MAX31865RTD至数字输出转换器引脚配置员8豆GND1 1610 GND2NC.179 FORCEM4X31865DVDD 197RTDIN+1}:2}:3;:41:5去TQFN(5mm x 5mm)TOP VIEWDRDY20」NC.DVDD 219 GNDBIASMA×3186517SD0REFIN+ 5REFIN-6ISENSOR14|SDFORCE2 9RTDIN+ 1011RTDIN-SSOPwww.maximintegrated.com/cnMAX31865RTD至数字输出转换器引脚说明引脚名称功能TQFN SSOP4BAS偏置电压输出BAso5REFN+基准电压输入正端,连接至BAS。在REFN+和REN之间连接参考电阻。6REF|N-基准电压输入负端,在REFN+和REN之间连接参考电距。4ISENSOR RREF的低边,连接至REFN58 FORCE+高边RTD驱动,使用3线连接配置时,将其连接到 FORCE2。具有±45过压俱护。FORCE2|输入叶端,仅限3线配置。3线连接配置下将其连接OHCF+:2线或4线连接配置下,该引朋接地。具有±45V过压保护。10RIDN+RTD输入正端,具有+45V过压保护。8RTDN-RTD输入负端,具有±45V过压保护。912FORCE·低边RTD回路,具有±45V过压保护。13GND2模拟地,连接至GND1SD串行数据输入。1215SCLK串行数据时钟输入。1316低电平有效片选,CS置为低电平时使能丰口。1417SDO串行数据输出1518DGND数字地。19GND1模拟地,连接至GND217NC.不连接。DRDY低电平有效数据就绪推挽输出。数据寄存器出现新的转换结果时,DRDY置为低电平。对RTD电阻数据寄存器执行读操作时,DRDY恢复为高电平。192DVDD数字电源输入,连接至3.3∨电源,利用01μF电容旁路至DGND。20vD模拟电源输入,连接至33∨电源,利用01μF电容旁路至GND1。裸焊盘(封装背面),连接至GND1。仅适用于TQFN封装。www.maximintegrated.com/cn8MAX31865RTD至数字输出转换器方框图VDVDDVCDBIASGENERATORREFIN+REFINSCLKSERIALISENSORTATA RFGISTERS KhSDILOGICFORCEFORCE2DIGITAL LOGICN、3-WREONLYDIGITALRIDIN+50/60HZ DIGITALCOMPARATOR15-BTSINC FILTER∑AADCFAULT DETECTION±45PR0TEcT0NMASTER-INIT ATEDFAULT-DETECTIONADC STATEDEDYMACHINERIDINCYCLEFORCEMAX316GND2 GNDDGNDwww.maximintegrated.com/cnMAX31865RTD至数字输出转换器详细说明MAx31865是成熟的RTD数字转换器,内置15位模数转换PT100 RTD RESISTANCE器(ADC)、输入保护、数字控制器、SP兼容接匚以及相关VS, TEMPERATURE的控制逻辑电路。信号调理电路优化用于PT100-PT1000RTD,也支持其它热敏电阻。50温度转换STRAIGHT-LINI3300APPROXIMATION电阻温度检测器iRTD是一种阻值随温度变化的电阻。铂是最棠见、精度最高的测温金属丝材料。铂RTD称为出至∽出∽200PT-RTD,镍、铜和其它金属亦可用来制造RTD。RTD具有RTD RESISTANCE较宽的测温范围,最高达+800°C,具有较高精度和较好的100可重复性,线性度适中。50对于 PT-RID,最常见的电阻是:O°C下标称值为1002和1kQ,当然也有其它阻值。0°C和+100°C之间的平均斜率称200-1000100200300400500600700为阿尔法(a),斜率与铂的杂质及密度有关。最常见的两个aTEMPERATURE (C)值是:0.00385和0.00392,分别对应于EC751(PT100)和SAMA标准。图3.Pt100RTD电阻与温度的关系m线阻值与温度的关系曲线接近线性,但有一定弯由,可由Callendar-∨ an dusen方程表示参考电阻的电流同栏流过RTD。参考电阻两端的电压为R(T)=R0(1+aT+bT2+c(T-100T3)ADC基准电压。RTD电压连接至ADC差分输入(RTD|N+式中和RTDN-)。所以ADC产生的数字输出等于RTD电阻与参考电阻的比值。对于铂电阻RTD,选择阻值等于RTD0°CT=温度(°C阻值的4倍的参考电阻最为合适。因此,针对PT100选用R行T)=T温下的阻值400参考电阻;针对PT1000则选用4k参考电阼Ro=T为0°C时的阻值如果RTD位于MAX31865附近,采用2线连接(典型应用电路)即可获得较好的测试结果。注意,对于PT100,0.49EC751规定=0.00385055及下列 Callendar-Van Dusen串联电阻引起的误差大约为1°C;因此,电缆长度增加时系数电缆电阻会引起过大的误差。a=390830×1034线连接通过使用独立的加载、检测(感应)引脚,消除了电b=-5.77500×10-7缆申阻引起的误差。当-200°C≤T≤0°C时,c=-4.18301×10-12;当0°C≤3线连接是一种折中方案,比4线方案少一条引线。为补偿T≤+850°C时,c=0。导线上的压降,从(RTD|N+-RTD|N)中减去 FORCE+和图3所示为PT100RTD的电阻随温度的变化曲线:根据O° RTDIN+之间的电压,利用 FORCE2对输入采样实现。如果至+100°C之间的斜率进行直线逼近。电缆电阻具有很好的一致性,即可消除电缆电阻引入的误为测量RTD阻值,接入参考电阻RRE),该电阻与RTD串差。将配置寄存器的3线位置1,选择3线工作模式。联,偏置电压作用在RREF上端,如典型应用电路所示。www.maximintegrated.com/cn