AD694手册

FUNCTIONALBLOCKDIAGRAMREV.BInformationfurnishedbyAnalogDevicesisbelievedtobeaccurateandreliable.However,noresponsibilityisassumedbyAnalogDevicesforitsuse,norforanyinfringementsofpatentsorotherrightsofthirdpartiesthatmayresultfromitsuse.NolicenseisgrantedbyimplicationorotherwiseunderanypatentorpatentrightsofAnalogDevices.a4–20mATransmitterAD694FEATURES4–20mA,0–20mAOutputRangesPrecalibratedInputRanges:0Vto2V,0Vto10VPrecisionVoltageReferenceProgrammableto2.000Vor10.000VSingleorDualSupplyOperationWidePowerSupplyRange:4.5Vto36VWideOutputComplianceInputBufferAmplifierOpen-LoopAlarmOptionalExternalPassTransistortoReduceSelf-HeatingErrors0.002%TypNonlinearityPRODUCTDESCRIPTIONTheAD694isamonolithiccurrenttransmitterthatacceptshighlevelsignalinputstodriveastandard4–20mAcurrentloopforthecontrolofvalves,actuators,andotherdevicescom-monlyusedinprocesscontrol.TheinputsignalisbufferedbyaninputamplifierthatcanbeusedtoscaletheinputsignalorbuffertheoutputfromacurrentmodeDAC.Precalibratedin-putspansof0Vto2Vand0Vto10Vareselectedbysimplepinstrapping;otherspansmaybeprogrammedwithexternalresistors.Theoutputstagecomplianceextendstowithin2VofVSanditsspecialdesignallowstheoutputvoltagetoextendbelowcommonindualsupplyoperation.Analarmwarnsofanopen4–20mAloopornoncomplianceoftheoutputstage.ActivelasertrimmingoftheAD694’sthinfilmresistorsresultsinhighlevelsofaccuracywithouttheneedforadditionaladjust-mentsandcalibration.AnexternalpasstransistormaybeusedwiththeAD694tooff-loadpowerdissipation,extendingthetemperaturerangeofoperation.TheAD694istheidealbuildingblockforsystemsrequiringnoiseimmune4–20mAsignaltransmissiontooperatevalves,actuators,andothercontroldevices,aswellasforthetransmis-sionofprocessparameterssuchaspressure,temperature,orflow.Itisrecommendedasareplacementfordiscretedesignsinavarietyofapplicationsinindustrialprocesscontrol,factoryautomation,andsystemmonitoring.TheAD694isavailableinhermeticallysealed,16-pinCERDIPandplasticSOIC,specifiedoverthe–40°Cto+85°Cindustrialtemperaturerange,andina16-pinplasticDIP,specifiedoverthe0°Cto+70°Ctemperaturerange.OneTechnologyWay,P.O.Box9106,Norwood,MA02062-9106,U.S.A.Tel:[phone]©AnalogDevices,Inc.,2002PRODUCTHIGHLIGHTS1.TheAD694isacompletevoltageinto4–20mAoutcurrenttransmitter.2.Pinprogrammableinputrangesareprecalibratedat0Vto2Vand0Vto10V.3.Theinputamplifiermaybeconfiguredtobufferandscaletheinputvoltage,ortoserveasanoutputamplifierforcurrentoutputDACs.4.Theoutputvoltagecomplianceextendstowithin2Vofthepositivesupplyandbelowcommon.Whenoperatedwitha5Vsupply,theoutputvoltagecomplianceextends30Vbe-lowcommon.5.TheAD694interfacesdirectlyto8-,10-,and12-bitsinglesupplyCMOSandbipolarDACs.6.The4mAzerocurrentmaybeswitchedonandoffwithaTTLcontrolpin,allowing0–20mAoperation.7.Anopencollectoralarmwarnsofloopfailureduetoopenwiresornoncomplianceoftheoutputstage.8.Amonitoredoutputisprovidedtodriveanexternalpasstransistor.Thefeatureoff-loadspowerdissipationtoextendthetemperaturerangeofoperationandminimizeself-heatingerror.AD694–SPECIFICATIONSModelAD694JN/AQ/ARAD694BQ/BRMinTypMaxMinTypMaxUnitINPUTCHARACTERISTICSInputVoltageRange–0.2VS–2.0VVS–2.5V–0.2VS–2.0VVS–2.5VVInputBiasCurrentEitherInput,TMINtoTMAX1.551.55nAOffsetCurrent,TMINtoTMAX±0.1
1±0.1
1nAOffsetCurrentDrift±1.0±5.0±1.0±5.0pA/°CInputImpedance55MΩOUTPUTCHARACTERISTICSOperatingCurrentRange023023mASpecifiedPerformance420420mAOutputVoltageComplianceVS–36VVS–2VVS–36VVS2VVOutputImpedance,4–20mA40.050.040.050.0MΩCurrentLimit(@2×FSOverdrive24442444mASlewRate1.31.3mA/µsSPANANDZEROACCURACY14mAOffsetError@0VInput2Errorfrom4.000mA,4mAOn±10
20±5
10µAErrorfrom0.000mA,4mAOff0+10+200+5+10µATMINtoTMAX±10
40±5
20µAvs.Supply(2VSpan/10VSpan)0.3/0.050.8/0.40.3/0.050.8/0.4µA/VTrimRange,4mAZero2.04.82.04.8mASpanNominalTransferFunctionInputFS=2V8.08.0mA/VInputFS=10V1.61.6mA/VTransferFunctionErrorfromNom,InputFS=2V,10V±0.1
0.3±0.05
0.15%ofSpanTMINtoTMAX±0.002±0.005±0.001
0.0025%ofSpan/°Cvs.Supply±0.001
0.005±0.001
0.005%ofSpan/VNonlinearity3±0.005
0.015±0.001
0.005%ofSpan4mAOn:MaxPin9Voltage0.80.8V4mAOff:MinPin9Voltage3.02.53.02.5VVOLTAGEREFERENCEOutputVoltage:10VReference9.96010.00010.0409.98010.00010.020VOutputVoltage:2VReference1.9922.0002.0081.9962.0002.004VTMINtoTMAX430502030ppm/°Cvs.Load,VREF=2V,10V0.150.500.150.50mV/mAvs.Supply,VREF=2V,10V±0.001
0.005±0.001
0.005%/VOutputCurrentSource55mASink0.20.2mAALARMCHARACTERISTICSVCE(SAT)@2.5mA0.350.35VLeakageCurrent
1
1µAAlarmPinCurrent(Pin10)2020mAPOWERREQUIREMENTSSpecifiedPerformance2424VOperatingRange2VFS,VREF=2V4.5364.536V2V,10VFS,VREF=2V,10V12.53612.536VQuiescentCurrent,4mAOff1.52.01.52.0mATEMPERATURERANGESpecifiedPerformance5AD694AQ/BQ/AR/BR–40+85–40+85°CAD694JN0+700+70°COperatingAD694AQ/BQ/AR/BR–55+125–55+125°CAD694JN–40+85–40+85°C(@+25C,RL=250,andVS=+24V,unlessotherwisenoted.)REV.B–2–ModelAD694JN/AQ/ARAD694BQ/BRMinTypMaxMinTypMaxUnitBUFFERAMPLIFIER6InputOffsetVoltageInitialOffset±150
500±50
500µVTMINtoTMAX±2±3±2±3µV/°Cvs.Supply80908090dBvs.CommonMode80908090dBTrimRange
2.5±4.0
2.5±4.0mVFr