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INA337INA338SBOS248–JUNE2002www.
ti.
comDESCRIPTIONTheINA337andINA338(withshutdown)arehightempera-ture,high-performance,low-cost,precisioninstrumentationamplifiers.
Theyaretruesingle-supplyinstrumentationampli-fierswithvery-lowDCerrorsandinputcommon-moderangesthatextendsbeyondthepositiveandapproachesthenega-tiverail.
Thesefeaturesmakethemsuitableforapplicationsrangingfromgeneral-purposetohigh-accuracy.
Excellentlong-termstabilityandverylow1/fnoiseassurelowoffsetvoltageanddriftthroughoutthelifeoftheproduct.
TheINA337(withoutshutdown)comesintheMSOP-8pack-age.
TheINA338(withshutdown)isofferedinMSOP-10.
Botharespecifiedoverthetemperaturerange,–40°Cto+125°C.
FEATURESqPRECISIONLOWOFFSET:100V(max)LOWOFFSETDRIFT:0.
4V/°C(max)EXCELLENTLONG-TERMSTABILITYVERY-LOW1/fNOISEqSMALLSIZEmicroPACKAGE:MSOP-8,MSOP-10qLOWCOSTPRODUCTIONDATAinformationiscurrentasofpublicationdate.
ProductsconformtospecificationsperthetermsofTexasInstrumentsstandardwarranty.
Productionprocessingdoesnotnecessarilyincludetestingofallparameters.
Copyright2002,TexasInstrumentsIncorporatedWide-Temperature,PrecisionINSTRUMENTATIONAMPLIFIERPleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
APPLICATIONSqLOW-LEVELTRANSDUCERAMPLIFIERFORBRIDGES,LOADCELLS,THERMOCOUPLESqWIDEDYNAMICRANGESENSORMEASUREMENTSqHIGH-RESOLUTIONTESTSYSTEMSqWEIGHSCALESqMULTI-CHANNELDATAACQUISITIONSYSTEMSqMEDICALINSTRUMENTATIONqAUTOMOTIVEAPPLICATIONSqGENERAL-PURPOSEINA337ANDINA338RELATEDPRODUCTSPRODUCTFEATURESINA326Precision,Rail-to-RailI/O,2.
4mAIQINA11450VVOS,0.
5nAIB,115dBCMR,3mAIQ,0.
25V/°CdriftINA11850VVOS,1nAIB,120dBCMR,385AIQ,0.
5V/°CdriftINA122250VVOS,–10nAIB,85AIQ,Rail-to-RailOutput,3V/°CdriftINA12850VVOS,2nAIB,125dBCMR,750AIQ,0.
5V/°CdriftINA321500VVOS,0.
5pAIB,94dBCMRR,60AIQ,Rail-to-RailOutputINA337R1R2C2VIN–VIN+7V+4V–VO562183G=2(R2/R1)INA338INA337INA337,INA3382SBOS222Awww.
ti.
comSPECIFIEDPACKAGETEMPERATUREPACKAGEORDERINGTRANSPORTPRODUCTPACKAGE-LEADDESIGNATOR(1)RANGEMARKINGNUMBERMEDIA,QUANTITYINA337MSOP-8DGK–40°Cto+125°CBIMINA337AIDGKTTapeandReel,250INA337AIDGKRTapeandReel,2500INA338MSOP-10DGS–40°Cto+125°CBILINA338AIDGSTTapeandReel,250INA338AIDGSRTapeandReel,2500NOTE:(1)Forthemostcurrentspecificationsandpackageinformation,refertoourwebsiteatwww.
ti.
com.
PACKAGE/ORDERINGINFORMATIONABSOLUTEMAXIMUMRATINGS(1)SupplyVoltage5.
5VSignalInputTerminals:Voltage(2)0.
5Vto(V+)+0.
5VCurrent(2)10mAOutputShort-CircuitContinuousOperatingTemperatureRange40°Cto+150°CStorageTemperatureRange65°Cto+150°CJunctionTemperature150°CLeadTemperature(soldering,10s)300°CNOTES:(1)Stressesabovetheseratingsmaycausepermanentdamage.
Exposuretoabsolutemaximumconditionsforextendedperiodsmaydegradedevicereliability.
Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthosespecifiedisnotimplied.
(2)Inputterminalsarediodeclampedtothepower-supplyrails.
Inputsignalsthatcanswingmorethan0.
5Vbeyondthesupplyrailsshouldbecurrentlimitedto10mAorless.
ELECTROSTATICDISCHARGESENSITIVITYThisintegratedcircuitcanbedamagedbyESD.
TexasInstrumentsrecommendsthatallintegratedcircuitsbehandledwithappropriateprecautions.
Failuretoobserveproperhan-dlingandinstallationprocedurescancausedamage.
ESDdamagecanrangefromsubtleperformancedegrada-tiontocompletedevicefailure.
Precisionintegratedcircuitsmaybemoresusceptibletodamagebecauseverysmallparametricchangescouldcausethedevicenottomeetitspublishedspecifications.
12348765R1V+VOR2R1VIN–VIN+V–INA337MSOP-812345109876R1V+VOR2EnableR1VIN–VIN+V–(ConnecttoV+)INA338MSOP-10TopViewPINCONFIGURATIONINA337,INA3383SBOS222Awww.
ti.
comELECTRICALCHARACTERISTICS:VS=+2.
7Vto+5.
5VBOLDFACElimitsapplyoverthespecifiedtemperaturerange,TA=–40°Cto+125°CAtTA=+25°C,RL=10k,G=100(R1=2k,R2=100k),externalgainsetresistors,andIACOMMON=VS/2,withexternalequivalentfiltercornerof1kHzfilters,unlessotherwisenoted.
INA337AIDGK,INA338AIDGSPARAMETERCONDITIONMINTYPMAXUNITSINPUTOffsetVoltage,RTIVOSVS=+5V,VCM=VS/2±20±100VOverTemperature±140VvsTemperaturedVOS/dT±0.
1±0.
4V/°CvsPowerSupplyPSRVS=+2.
7Vto+5.
5V,VCM=VS/2±20±3V/VLong-TermStabilitySeeNote(1)InputImpedance,Differential1010||2||pFCommon-Mode1010||14||pFInputVoltageRange(V–)+0.
25(V+)+0.
1VSafeInputVoltage(V–)–0.
5(V+)+0.
5VCommon-ModeRejectionCMRVS=+5V,VCM=(V–)+0.
25Vto(V+)+0.
1V106120dBOverTemperature100dBINPUTBIASCURRENTVCM=VS/2BiasCurrentIBVS=+5V±0.
2±2nAvsTemperatureSeeTypicalCharacteristicsOffsetCurrentIOSVS=+5V±0.
2±2nANOISEVoltageNoise,RTIRS=0,G=100,R1=2k,R2=100kf=10Hz33nV/√Hzf=100Hz33nV/√Hzf=1kHz33nV/√Hzf=0.
01Hzto10Hz0.
8Vp-pVoltageNoise,RTIRS=0,G=10,R1=20k,R2=100kf=10Hz120nV/√Hzf=100Hz97nV/√Hzf=1kHz97nV/√Hzf=0.
01Hzto10Hz4Vp-pCurrentNoise,RTIf=1kHz0.
15pA/√Hzf=0.
01Hzto10Hz4.
2pAp-pOutputRipple,VOFiltered(2)SeeApplicationsInformationGAINGainEquationG=2(R2/R1)RangeofGain10000V/VGainError(3)G=10,100,VS=+5V,VO=0.
25Vto4.
925V0.
08±0.
2%vsTemperatureG=10,100,VS=+5V,VO=0.
25Vto4.
925V±6±25ppm/°CNonlinearityG=10,100,VS=+5V,VO=0.
25Vto4.
925V±0.
003±0.
01%ofFSOUTPUTVoltageOutputSwingfromPositiveRailRL=10k,VS=5V(V+)–0.
075(V+)–0.
01VOverTemperature(V+)–0.
075VVoltageOutputSwingfromNegativeRailRL=10k,VS=5V(V–)+0.
25(V+)+0.
01VOverTemperature(V–)+0.
25VCapacitiveLoadDrive500pFShort-CircuitCurrentISC±25mAINTERNALOSCILLATORFrequencyofAuto-Correction90kHzAccuracy±20%FREQUENCYRESPONSEBandwidth(4),–3dBBWG=1to1k1kHzSlewRate(4)SRVS=5V,AllGains,CL=100pFFilterLimitedSettlingTime(4),0.
1%tS1kHzFilter,G=1to1k,VO=2Vstep,CL=100pF0.
95ms0.
01%1.
3ms0.
1%10kHzFilter,G=1to1k,VO=2Vstep,CL=100pF130s0.
01%160sOverloadRecovery(4)1kHzFilter,50%OutputOverload,G=1to1k30s10kHzFilter,50%OutputOverload,G=1to1k5sINA337,INA3384SBOS222Awww.
ti.
comPARAMETERCONDITIONMINTYPMAXUNITSPOWERSUPPLYSpecifiedVoltageRange+2.
7+5.
5VQuiescentCurrentIQIO=0,DiffVIN=0V,VS=+5V2.
43.
4mAOverTemperature3.
7mASHUTDOWNDisable(Logic-LowThreshold)0.
25VEnable(Logic-HighThreshold)1.
6VEnableTime(5)75sDisableTime100sShutdownCurrentandEnablePinCurrentVS=+5V,Disabled25ATEMPERATURERANGESpecifiedRange–40+125°COperatingRange–40+150°CStorageRange–65+150°CThermalResistanceθJAMSOP-8Surface-Mount150°C/WNOTES:(1)1000-hourlifetestat150°Cdemonstratedrandomlydistributedvariationintherangeofmeasurementlimits—approximately10V.
(2)SeeApplicationsInformationsection,Figures1and2.
(3)DoesnotincludeerrorandTCRofexternalgain-settingresistors.
(4)Dynamicresponseislimitedbyfiltering.
Higherbandwidthscanbeachievedbyadjustingthefilter.
(5)SeeTypicalCharacteristics,"InputOffsetVoltagevsWarm-UpTime".
ELECTRICALCHARACTERISTICS:VS=+2.
7Vto+5.
5V(Cont.
)BOLDFACElimitsapplyoverthespecifiedtemperaturerange,TA=–40°Cto+125°CAtTA=+25°C,RL=10k,G=100(R1=2k,R2=100k),externalgainsetresistors,andIACOMMON=VS/2,withexternalequivalentfiltercornerof1kHzfilters,unlessotherwisenoted.
INA337AIDGK,INA338AIDGSINA337,INA3385SBOS222Awww.
ti.
comTYPICALCHARACTERISTICSAtTA=25°C,VS=+5V,Gain=100,RL=10kwithexternalequivalentfiltercornerof1kHzfilters,unlessotherwisenoted.
GAINvsFREQUENCY1kHzFILTERFrequency(Hz)101001k10k100k1MGain(dB)806040200–20–40G=1kG=100G=10G=1GAINvsFREQUENCY10kHzFILTERFrequency(Hz)101001k10k100k1MGain(dB)806040200–20–40G=1kG=100G=10G=1INPUT-REFERREDVOLTAGENOISEANDINPUTBIASCURRENTNOISEvsFREQUENCY10kHzFilter110k1k1001010.
10.
010.
001101001k10kFrequency(Hz)Input-ReferredVoltageNoise(nV/√Hz)InputBiasCurrentNoise(pA/√Hz)G=1G=100CurrentNoise(allgains)G=10G=1000CMRvsFREQUENCY1kHzFILTERFrequency(Hz)101001k10k100k1MCMR(dB)16014012010080604020G=1kG=100G=10G=1CMRvsFREQUENCY10kHzFILTERFrequency(Hz)101001k10k100k1MCMR(dB)16014012010080604020G=100G=10G=1G=1kPOWER-SUPPLYREJECTIONvsFREQUENCYFrequency(Hz)101001k10k100kPSR(dB)120100806040200G=100,1kG=10G=1FilterFrequency10kHz1kHzINA337,INA3386SBOS222Awww.
ti.
comTYPICALCHARACTERISTICS(Cont.
)AtTA=25°C,VS=+5V,Gain=100,RL=10kwithexternalequivalentfiltercornerof1kHzfilters,unlessotherwisenoted.
SMALL-SIGNALRESPONSEG=1,10,AND10050mV/div500s/div1kHzFilter10kHzFilterSMALL-SIGNALSTEPRESPONSEG=100050mV/div500s/div1kHzFilterLARGE-SIGNALRESPONSEG=1TO10002V/div500s/div1kHzFilter10kHzFilterINPUTOFFSETVOLTAGEvsTURN-ONTIME1kHzFILTER,G=100InputOffsetVoltage(20V/div)102Turn-OnTime(ms)FilterSettlingTimeDeviceTurn-OnTime(75s)INPUTOFFSETVOLTAGEvsWARM-UPTIME10kHzFILTER,G=100InputOffsetVoltage(20V/div)0.
20.
300.
10.
4Warm-UpTime(ms)FilterSettlingTimeDeviceTurn-OnTime0.
01HzTO10HzVOLTAGENOISE200nV/div10s/divINA337,INA3387SBOS222Awww.
ti.
comTYPICALCHARACTERISTICS(Cont.
)AtTA=25°C,VS=+5V,Gain=100,RL=10kwithexternalequivalentfiltercornerof1kHzfilters,unlessotherwisenoted.
OFFSETVOLTAGEPRODUCTIONDISTRIBUTIONG=1OffsetVoltage(V)–10,000–9000–8000–7000–6000–5000–4000–3000–2000–1000010002000300040005000600070008000900010,000PopulationOFFSETVOLTAGEDRIFTPRODUCTIONDISTRIBUTIONG=1OffsetVoltageDrift(V/°C)0246810121416182022242628303234363840PopulationOFFSETVOLTAGEPRODUCTIONDISTRIBUTIONG=10OffsetVoltage(V)–1000–900–800–700–600–500–400–300–200–10001002003004005006007008009001000PopulationOFFSETVOLTAGEDRIFTPRODUCTIONDISTRIBUTIONG=10OffsetVoltageDrift(V/°C)Population0.
00.
20.
40.
60.
81.
01.
21.
41.
61.
82.
02.
22.
42.
62.
83.
03.
23.
43.
63.
84.
0OFFSETVOLTAGEPRODUCTIONDISTRIBUTIONG=100and1000OffsetVoltage(V)1009080706050403020100102030405060708090100PopulationOFFSETVOLTAGEDRIFTPRODUCTIONDISTRIBUTIONG=100and1000OffsetVoltageDrift(V/°C)Population0.
00.
20.
40.
60.
80.
10.
120.
140.
160.
180.
20.
220.
240.
260.
280.
30.
320.
340.
360.
380.
4INA337,INA3388SBOS222Awww.
ti.
comTYPICALCHARACTERISTICS(Cont.
)AtTA=25°C,VS=+5V,Gain=100,RL=10kwithexternalequivalentfiltercornerof1kHzfilters,unlessotherwisenoted.
INPUTBIASCURRENTvsTEMPERATURETemperature(°C)IB(nA)2.
01.
51.
00.
50–0.
5–1.
0–1.
5–2.
0IB–IB+–4040200–201201008060QUIESCENTCURRENTvsTEMPERATURETemperature(°C)–50–250255075100125IQ(mA)3.
02.
52.
01.
51.
00.
50VS=+2.
7VVS=+5VGAINERRORPRODUCTIONDISTRIBUTIONGainError(m%)–200–180–160–140–120–100–80–60–40–20020406080100120140160180200PopulationINPUT-REFERREDRIPPLESPECTRUMG=100Frequency(Hz)0200k400k600k800k1MVOUT(dBV)100110120130140150160170180VOUT(Vrms)10031.
610.
3160.
100.
030.
010.
0030.
001OUTPUTSWINGTOTHENEGATIVERAILvsTEMPERATUREOutputSwingtoNegativeRail(mV)–40161412108642040200–20Temperature(°C)1201008060INA337,INA3389SBOS222Awww.
ti.
comINA337VOFilteredVO6G=2(R2/R1)fO=1kHzRO100CO(1)1FR2C2(1)7V+40.
1FV–5Single-SupplyOperationIACOMMON(2)IACOMMON(2)INA337R1R1VIN–VIN+VOFilteredVO62183G=2(R2/R1)fO=1kHzRO100CO(1)1FR2C2(1)7+2.
5V40.
1F–2.
5V5Dual-SupplyOperationNOTES:(1)C2andCOcombinetoforma2-poleresponsethatis–3dBat1kHz.
Eachindividualpoleisat1.
5kHz.
(2)OutputvoltageisreferencedtoIACOMMON(seetext).
NOTES:(1)C2andCOcombinetoforma2-poleresponsethatis–3dBat1kHz.
Eachindividualpoleisat1.
5kHz.
(2)OutputvoltageisreferencedtoIACOMMON(seetext).
(3)Outputpedestalrequiredformeasurementnearzero(seeFigure6).
18VIN–VIN+23(3)DESIREDR1R2||C2GAINnF)0.
1400k20k||50.
2400k40k||2.
50.
5400k100k||11400k200k||0.
52200k200k||0.
5580k200k||0.
51040k200k||0.
52020k200k||0.
5508k200k||0.
51004k200k||0.
52002k200k||0.
55002k500k||0.
210002k1M||0.
120002k2M||0.
0550002k5M||0.
02100002k10M||0.
01APPLICATIONSINFORMATIONFigure1showsthebasicconnectionsrequiredforoperationoftheINA337.
A0.
1Fcapacitor,placedclosetoandacrossthepower-supplypinsisstronglyrecommendedforhighestaccu-racy.
RoCoisanoutputfilterthatminimizesauto-correctioncircuitrynoise.
Thisoutputfiltermayalsoserveasananti-aliasingfilteraheadofanAnalog-to-Digital(A/D)converter.
Itisalsooptionalbasedondesiredprecision.
TheoutputreferenceterminalistakenatthelowsideofR2(IACOMMON).
TheINA337usesauniqueinternaltopologytoachieveexcel-lentcommon-moderejection(CMR).
Unlikeconventionalin-strumentationamplifiers,CMRisnotaffectedbyresistanceinthereferenceconnections.
See"InsidetheINA337"forfurtherdetail.
Toachievebesthigh-frequencyCMR,minimizecapaci-tanceonpins1and8.
FIGURE1.
BasicConnections.
NOTE:ConnectionsforINA338differ—seePinConfigurationfordetail.
SETTINGTHEGAINTheINA337isa2-stageamplifierwitheachstagegainsetbyR1andR2,respectively(seeFigure4,"InsidetheINA337",fordetails.
)Overallgainisdescribedbytheequation:GRR=221(1)Thestabilityandtemperaturedriftoftheexternalgain-settingresistorswillaffectgainbyanamountthatcanbedirectlyinferredfromthegainequation(1).
ResistorvaluesforcommonlyusedgainsareshowninFigure1.
Gain-setresistorvaluesforbestperformancearedifferentfor+5Vsingle-supplyandfor±2.
5Vdual-supplyoperation.
OptimumvalueforR1canbecalculatedby:R1=VIN,MAX/12.
5A(2)whereR1mustbenolessthan2k.
DESIREDR1R2||C2GAINnF)0.
1400k20k||50.
2400k40k||2.
50.
5400k100k||11200k100k||12100k100k||1540k100k||11020k100k||12010k100k||1504k100k||11002k100k||12002k200k||0.
55002k500k||0.
210002k1M||0.
120002k2M||0.
0550002k5M||0.
02100002k10M||0.
01INA337,INA33810SBOS222Awww.
ti.
comFollowingthisdesignprocedureforR1producesthemaxi-mumpossibleinputstagegainforbestaccuracyandlowestnoise.
Circuitlayoutandsupplybypassingcanaffectperformance.
Minimizethestraycapacitanceonpins1and8.
Userecom-mendedsupplybypassing,includingacapacitordirectlyfrompin7topin4(V+toV–),evenwithdual(split)powersupplies(seeFigure1).
DYNAMICPERFORMANCEThetypicalcharacteristic"GainvsFrequency"showsthattheINA337hasnearlyconstantbandwidthregardlessofgain.
Thisresultsfromthebandwidthlimitingfromtherecom-mendedfilters.
NOISEPERFORMANCEInternalauto-correctioncircuitryeliminatesvirtuallyall1/fnoise(noisethatincreasesatlowfrequency)ingainsof100orgreater.
Noiseperformanceisaffectedbygain-settingresistorvalues.
Followrecommendationsinthe"SettingGain"sectionforbestperformance.
Totalnoiseisacombinationofinputstagenoiseandoutputstagenoise.
Whenreferredtotheinput,thetotalmid-bandnoiseis:VnVHznVHzGN=+33800//(3)Theoutputnoisehassome1/fcomponentsthataffectperformanceingainslessthan10.
Seetypicalcharacteristic"Input-ReferredVoltageNoisevsFrequency.
"High-frequencynoiseiscreatedbyinternalauto-correctioncircuitryandishighlydependentonthefiltercharacteristicschosen.
Thismaybethedominantsourceofnoisevisiblewhenviewingtheoutputonanoscilloscope.
Lowcutofffrequencyfilterswillprovidelowestnoise.
Figure2showsthetypicalnoiseperformanceasafunctionofcutofffrequency.
Applicationssensitivetothespectralcharacteristicsofhigh-frequencynoisemayrequireconsiderationofthespuriousfrequenciesgeneratedbyinternalclockingcircuitry.
"Spurs"occuratapproximately90kHzanditsharmonics(seetypicalcharacteristic"InputReferredRipple")whichmaybereducedbyadditionalfilteringbelow1kHz.
Insufficientfilteringatpin5cancausenonlinearitywithlargeoutputvoltageswings(verynearthesupplyrails).
Noisemustbesufficientlyfilteredatpin5sothatnoisepeaksdonot"hittherail"andchangetheaveragevalueofthesignal.
Figure2showsguidelinesforfiltercutofffrequency.
HIGH-FREQUENCYNOISEC2andCOformfilterstoreduceinternallygeneratedauto-correctioncircuitrynoise.
Filterfrequenciescanbechosentooptimizethetradeoffbetweennoiseandfrequencyresponseoftheapplication,asshowninFigure2.
Thecutofffrequen-ciesofthefiltersaregenerallysettothesamefrequency.
Figure2showsthetypicaloutputnoiseforfourgainsasafunctionofthe–3dBcutofffrequencyofeachfilterresponse.
Smallsignalsmayexhibittheadditionofinternallygeneratedauto-correctioncircuitrynoiseattheoutput.
Thisnoise,combinedwithbroadbandnoise,becomesmostevidentinhighergainswithfiltersofwiderbandwidth.
INPUTBIASCURRENTRETURNPATHTheinputimpedanceoftheINA337isextremelyhigh—approximately1010.
However,apathmustbeprovidedfortheinputbiascurrentofbothinputs.
Thisinputbiascurrentisapproximately±0.
2nA.
Highinputimpedancemeansthatthisinputbiascurrentchangesverylittlewithvaryinginputvoltage.
Inputcircuitrymustprovideapathforthisinputbiascurrentforproperoperation.
Figure3showsprovisionsforaninputbiascurrentpathinathermocoupleapplication.
Withoutabiascurrentpath,theinputswillfloattoanundefinedpoten-tialandtheoutputvoltagemaynotbevalid.
FIGURE2.
TotalOutputNoisevsFilterCutoffFrequency.
1001101k10kRequiredFilterCutoffFrequency(Hz)TotalOutputNoise(VRMS)1k100101G=10G=1G=100G=1000INA337Thermocouple5FIGURE3.
ProvidingInputBiasCurrentReturnPath.
INA337,INA33811SBOS222Awww.
ti.
comINPUTANDOUTPUTVOLTAGETheINA337andINA338featurenearlyrail-to-railinputbehavior,withthelinearinputvoltagerangeextendingfrom0.
25Vabovethenegativerailto0.
1Vabovethepositiverail.
Theoutputisabletoswingtowithin0.
25Vofthenegativerailand0.
075Vofthepositiverail.
SeeTypicalCharacteristicsCurve"OutputSwingtotheNegativeRail"foradditionaldetail.
TheINA337usesanew,uniqueinternalcircuittopologythatprovidesnearrail-to-railinput.
Unlikeotherinstru-mentationamplifiers,itcanlinearlyprocessinputsfrom0.
25Vabovethenegativerailto0.
1Vbeyondthepositiverail.
Conventionalinstrumentationamplifiercircuitscannotdeliversuchperformance,evenifrail-to-railopampsareused.
Theabilitytorejectcommon-modesignalsisderivedinmostinstrumentationamplifiersthroughacombinationofamplifierCMRandaccuratelymatchedresistorratios.
TheINA337convertstheinputvoltagetoacurrent.
Current-modesignalprocessingprovidesrejectionofcommon-modeinputvoltageandpower-supplyvariationwithoutaccuratelymatchedresistors.
ThetopologyoftheINA337avoidsaliasingissuesthatappearininstrumentationamplifiersthatusesampleddatatechniques.
Asimplifieddiagramshowsthebasiccircuitfunction.
Thedifferentialinputvoltage,(VIN+)–(VIN–)isappliedacrossR1.
Thesignal-generatedcurrentthroughR1comesfromA1andA2'soutputstages.
A2combinesthecurrentinR1withamirroredreplicaofthecurrentfromA1.
Theresult-ingcurrentinA2'soutputandassociatedcurrentmirroristwotimesthecurrentinR1.
Thiscurrentflowsin(orout)ofpin5intoR2.
Theresultinggainequationis:GRR=221AmplifiersA1,A2andtheirassociatedmirrorsarepow-eredfrominternalcharge-pumpsthatprovidevoltagesuppliesthatarebeyondthepositivenegativesupply.
Asaresult,thevoltagedevelopedonR2canactuallyswing100mVabovethepositivepower-supplyrail.
A3providesabufferedoutputofthevoltageonR2.
A3'sinputstageisalsooperatedfromthecharge-pumpedpowersuppliesfortruerail-to-railoperation.
FIGURE4.
SimplifiedCircuitDiagram.
INSIDETHEINA337INPUTPROTECTIONTheinputsoftheINA337areprotectedwithinternaldiodesconnectedtothepower-supplyrails.
Thesediodeswillclamptheappliedsignaltopreventitfromdamagingtheinputcircuitry.
Iftheinputsignalvoltagecanexceedthepowersuppliesbymorethan0.
5V,theinputsignalcurrentshouldbelimitedtolessthan10mAtoprotecttheinternalclampdiodes.
Thiscangenerallybedonewithaseriesinputresistor.
Somesignalsourcesareinherentlycurrent-limitedanddonotrequirelimitingresistors.
A1V+V–CurrentMirrorCurrentMirrorIR1IR1IR1R1R2C2VOVIN–VIN+IR12IR12IR12IR12IR12IR1A3A2IACOMMON0.
1FCurrentMirrorCurrentMirrorINA337,INA33812SBOS222Awww.
ti.
com2k200k200kVREFRO5COC2VREFINA337A/DConverterG=2(200k||200k)/2k=100FIGURE6.
OutputRangePedestal.
FIGURE7.
High-SideShuntMeasurementofCurrentLoad.
FILTERINGFilteringcanbeadjustedthroughselectionofR2C2andROCOforthedesiredtradeoffofnoiseandbandwidth.
Adjust-mentofthesecomponentswillresultinmoreorlessrippleduetoauto-correctioncircuitrynoiseandwillalsoaffectbroadbandnoise.
Filteringlimitsslewrate,settlingtime,andoutputoverloadrecoverytime.
ItisgenerallydesirabletokeeptheresistanceofROrelativelylowtoavoidDCgainerrorcreatedbythesubsequentstageloading.
ThismayresultinrelativelyhighvaluesforCOtoproducethedesiredfilterresponse.
TheimpedanceofROCOcanbescaledhighertoproducesmallercapacitorvaluesiftheloadimpedanceisveryhigh.
Certaincapacitortypesgreaterthan0.
1Fmayhavedielec-tricabsorptioneffectsthatcansignificantlyincreasesettlingtimeinhigh-accuracyapplications(settlingto0.
01%).
Polypro-pylene,polystyrene,andpolycarbonatetypesaregenerallygood.
Certain"high-K"ceramictypesmayproduceslowsettling"tails.
"Settlingtimeto0.
1%isnotgenerallyaffectedbyhigh-Kceramiccapacitors.
ElectrolytictypesarenotrecommendedforC2andCO.
INA338ENABLEFUNCTIONTheINA338canbeenabledbyapplyingalogic"High"voltageleveltotheEnablepin.
Conversely,alogic"Low"voltagelevelwilldisabletheamplifier,reducingitssupplycurrentfrom2.
4mAtotypically2A.
Forbattery-operatedapplications,thisfeaturemaybeusedtogreatlyreducetheaveragecurrentandextendbatterylife.
Thispinshouldbeconnectedtoavalidhighorlowvoltageordriven,notleftopencircuit.
TheEnablepincanbemodeledasaCMOSinputgateasinFigure5.
R1R25R0R2C2C0VREF=10Vto5VG=2(R2||R2)/R1INA337R2andR2arechosentocreateasmallpedestalvoltage(e.
g.
,250mV).
GainisdeterminedbytheparallelcombinationofR2andR2.
INA337+5VIL5RORSR1R2C2CONOTE:ConnectionpointofV+willinclude()orexclude()quiescentcurrentinthemeasurementasdesired.
Outputpedestalrequiredformeasurementsnearzero(seeFigure6).
RSmustbechosensothattheinputvoltagedoesnotexceed100mVabovetherail.
FIGURE8.
OutputReferencedtoVREF/2.
FIGURE5.
EnablePinModel.
V+Enable62AV–Theenabletimefollowingshutdownis75splusthesettlingtimeduetofilters(seeTypicalCharacteristics,"InputOffsetVoltagevsWarm-upTime").
Disabletimeis100s.
ThisallowstheINA338tobeoperatedasa"gated"amplifier,ortohaveitsoutputmultiplexedontoacommonoutputbus.
Whendisabled,theoutputassumesahigh-impedancestate.
INA338PIN5Pin5oftheINA338shouldbeconnectedtoV+toensureproperoperation.
INA337,INA33813SBOS222Awww.
ti.
comPACKAGEDRAWINGSMPDS028B–JUNE1997–REVISEDSEPTEMBER2001DGK(R-PDSO-G8)PLASTICSMALL-OUTLINEPACKAGE0,690,410,250,15NOMGagePlane4073329/C08/014,980,2553,054,782,95843,052,9510,381,07MAXSeatingPlane0,65M0,080°–6°0,100,150,05NOTES:A.
Alllineardimensionsareinmillimeters.
B.
Thisdrawingissubjecttochangewithoutnotice.
C.
Bodydimensionsdonotincludemoldflashorprotrusion.
D.
FallswithinJEDECMO-187INA337,INA33814SBOS222Awww.
ti.
comPACKAGEDRAWINGS(Cont.
)MPDS035A–JANUARY1998–REVISEDSEPTEMBER2001DGS(S-PDSO-G10)PLASTICSMALL-OUTLINEPACKAGE0,690,410,250,15NOMGagePlane4073272/B08/014,980,1763,054,782,951053,052,9510,270,150,051,07MAXSeatingPlane0,100,50M0,080°–6°NOTES:A.
Alllineardimensionsareinmillimeters.
B.
Thisdrawingissubjecttochangewithoutnotice.
C.
Bodydimensionsdonotincludemoldflashorprotrusion.
A.
FallswithinJEDECMO-187PACKAGEOPTIONADDENDUMwww.
ti.
com10-Dec-2020Addendum-Page1PACKAGINGINFORMATIONOrderableDeviceStatus(1)PackageTypePackageDrawingPinsPackageQtyEcoPlan(2)Leadfinish/Ballmaterial(6)MSLPeakTemp(3)OpTemp(°C)DeviceMarking(4/5)SamplesINA337AIDGKRACTIVEVSSOPDGK82500RoHS&GreenNIPDAUAGLevel-2-260C-1YEAR-40to125BIMINA337AIDGKTACTIVEVSSOPDGK8250RoHS&GreenNIPDAUAGLevel-2-260C-1YEAR-40to125BIMINA337AIDGKTG4ACTIVEVSSOPDGK8250RoHS&GreenNIPDAUAGLevel-2-260C-1YEAR-40to125BIMINA338AIDGSTACTIVEVSSOPDGS10250RoHS&GreenNIPDAUAGLevel-2-260C-1YEAR-40to125BIL(1)Themarketingstatusvaluesaredefinedasfollows:ACTIVE:Productdevicerecommendedfornewdesigns.
LIFEBUY:TIhasannouncedthatthedevicewillbediscontinued,andalifetime-buyperiodisineffect.
NRND:Notrecommendedfornewdesigns.
Deviceisinproductiontosupportexistingcustomers,butTIdoesnotrecommendusingthispartinanewdesign.
PREVIEW:Devicehasbeenannouncedbutisnotinproduction.
Samplesmayormaynotbeavailable.
OBSOLETE:TIhasdiscontinuedtheproductionofthedevice.
(2)RoHS:TIdefines"RoHS"tomeansemiconductorproductsthatarecompliantwiththecurrentEURoHSrequirementsforall10RoHSsubstances,includingtherequirementthatRoHSsubstancedonotexceed0.
1%byweightinhomogeneousmaterials.
Wheredesignedtobesolderedathightemperatures,"RoHS"productsaresuitableforuseinspecifiedlead-freeprocesses.
TImayreferencethesetypesofproductsas"Pb-Free".
RoHSExempt:TIdefines"RoHSExempt"tomeanproductsthatcontainleadbutarecompliantwithEURoHSpursuanttoaspecificEURoHSexemption.
Green:TIdefines"Green"tomeanthecontentofChlorine(Cl)andBromine(Br)basedflameretardantsmeetJS709Blowhalogenrequirementsof<=1000ppmthreshold.
Antimonytrioxidebasedflameretardantsmustalsomeetthe<=1000ppmthresholdrequirement.
(3)MSL,PeakTemp.
-TheMoistureSensitivityLevelratingaccordingtotheJEDECindustrystandardclassifications,andpeaksoldertemperature.
(4)Theremaybeadditionalmarking,whichrelatestothelogo,thelottracecodeinformation,ortheenvironmentalcategoryonthedevice.
(5)MultipleDeviceMarkingswillbeinsideparentheses.
OnlyoneDeviceMarkingcontainedinparenthesesandseparatedbya"~"willappearonadevice.
IfalineisindentedthenitisacontinuationofthepreviouslineandthetwocombinedrepresenttheentireDeviceMarkingforthatdevice.
(6)Leadfinish/Ballmaterial-OrderableDevicesmayhavemultiplematerialfinishoptions.
Finishoptionsareseparatedbyaverticalruledline.
Leadfinish/Ballmaterialvaluesmaywraptotwolinesifthefinishvalueexceedsthemaximumcolumnwidth.
ImportantInformationandDisclaimer:TheinformationprovidedonthispagerepresentsTI'sknowledgeandbeliefasofthedatethatitisprovided.
TIbasesitsknowledgeandbeliefoninformationprovidedbythirdparties,andmakesnorepresentationorwarrantyastotheaccuracyofsuchinformation.
Effortsareunderwaytobetterintegrateinformationfromthirdparties.
TIhastakenandPACKAGEOPTIONADDENDUMwww.
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com10-Dec-2020Addendum-Page2continuestotakereasonablestepstoproviderepresentativeandaccurateinformationbutmaynothaveconducteddestructivetestingorchemicalanalysisonincomingmaterialsandchemicals.
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TAPEANDREELINFORMATION*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQReelDiameter(mm)ReelWidthW1(mm)A0(mm)B0(mm)K0(mm)P1(mm)W(mm)Pin1QuadrantINA337AIDGKRVSSOPDGK82500330.
012.
45.
33.
41.
48.
012.
0Q1INA337AIDGKTVSSOPDGK8250180.
012.
45.
33.
41.
48.
012.
0Q1INA338AIDGSTVSSOPDGS10250180.
012.
45.
33.
41.
48.
012.
0Q1PACKAGEMATERIALSINFORMATIONwww.
ti.
com16-Oct-2020PackMaterials-Page1*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQLength(mm)Width(mm)Height(mm)INA337AIDGKRVSSOPDGK82500853.
0449.
035.
0INA337AIDGKTVSSOPDGK8250210.
0185.
035.
0INA338AIDGSTVSSOPDGS10250210.
0185.
035.
0PACKAGEMATERIALSINFORMATIONwww.
ti.
com16-Oct-2020PackMaterials-Page2IMPORTANTNOTICEANDDISCLAIMERTIPROVIDESTECHNICALANDRELIABILITYDATA(INCLUDINGDATASHEETS),DESIGNRESOURCES(INCLUDINGREFERENCEDESIGNS),APPLICATIONOROTHERDESIGNADVICE,WEBTOOLS,SAFETYINFORMATION,ANDOTHERRESOURCES"ASIS"ANDWITHALLFAULTS,ANDDISCLAIMSALLWARRANTIES,EXPRESSANDIMPLIED,INCLUDINGWITHOUTLIMITATIONANYIMPLIEDWARRANTIESOFMERCHANTABILITY,FITNESSFORAPARTICULARPURPOSEORNON-INFRINGEMENTOFTHIRDPARTYINTELLECTUALPROPERTYRIGHTS.
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