有关A D模数转换的外文翻译.docx

有关A D模数转换的外文翻译.docx

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有关AD模数转换的外文翻译

中文4819字

ICL713541/2Digit,BCDOutput,A/DConverter

TheIntersilICL7135precisionA/Dconverter,withitsmultiplexedBCDoutputanddigitdrivers,combinesdual-slopeconversionreliabilitywith+1in20,000countaccuracyandisideallysuitedforthevisualdisplayDVM/DPMmarket.The2.0000Vfullscalecapability,auto-zero,andauto-polarityarecombinedwithtrueratiometricoperation,almostidealdifferentiallinearityandtruedifferentialinput.AllnecessaryactivedevicesarecontainedonasingleCMOSlC,withtheexceptionofdisplaydrivers,reference,andaclock.

TheICL7135bringstogetheranunprecedentedcombinationofhighaccuracy,versatility,andtrueeconomy.Itfeaturesauto-zerotolessthan10µV,zerodriftoflessthan1µV/℃,inputbiascurrentof10pA（Max）,androllovererroroflessthanonecount.TheversatilityofmultiplexedBCDoutputsisincreasedbytheadditionofseveralpinswhichallowittooperateinmoresophisticatedsystems.TheseincludeSTROBE,OVERRANGE,UNDERRANGE,RUN/HOLDandBUSYlines,makingitpossibletointerfacethecircuittoamicroprocessororUART.

Features

*AccuracyGuaranteedto+1CountOverEntire20000Counts（2.0000VFullScale）

*GuaranteedZeroReadingfor0VInput

*1pATypicalInputLeakageCurrent

*TrueDifferentialInput

*TruePolarityatZeroCountforPreciseNullDetection

*SingleReferenceVoltageRequired

*OverrangeandUnderrangeSignalsAvailableforAuto-RangeCapability

*AllOutputsTTLCompatible

*BlinkingOutputsGivesVisualIndicationofOverrange

*SixAuxiliaryInputs/OutputsareAvailableforInterfacingtoUARTs,Microprocessors,orOtherCircuitry

*MultiplexedBCDOutputs

*Pb-FreeAvailable（RoHSCompliant）

DetailedDescription

AnalogSection

Eachmeasurementcycleisdividedintofourphases.Theyare

（1）auto-zero（AZ）,

（2）signal-integrate（INT）,（3）de-integrate（DE）and（4）zero-integrator（Zl）.

Auto-ZeroPhase

Duringauto-zero,threethingshappen.First,inputhighandlowaredisconnectedfromthepinsandinternallyshortedtoanalogCOMMON.Second,thereferencecapacitorischargedtothereferencevoltage.Third,afeedbackloopisclosedaroundthesystemtochargetheauto-zerocapacitorCAZtocompensateforoffsetvoltagesinthebufferamplifier,integrator,andcomparator.Sincethecomparatorisincludedintheloop,theAZaccuracyislimitedonlybythenoiseofthesystem.Inanycase,theoffsetreferredtotheinputislessthan10µV.

SignalIntegratePhase

Duringsignalintegrate,theauto-zeroloopisopened,theinternalshortisremoved,andtheinternalinputhighandlowareconnectedtotheexternalpins.TheconverterthenintegratesthedifferentialvoltagebetweenINHIandINLOforafixedtime.Thisdifferentialvoltagecanbewithinawidecommonmoderange;withinonevoltofeithersupply.If,ontheotherhand,theinputsignalhasnoreturnwithrespecttotheconverterpowersupply,INLOcanbetiedtoanalogCOMMONtoestablishthecorrectcommon-modevoltage.Attheendofthisphase,thepolarityoftheintegratedsignalislatchedintothepolarityF/F.

De-IntegratePhase

Thethirdphaseisde-integrateorreferenceintegrate.InputlowisinternallyconnectedtoanalogCOMMONandinputhighisconnectedacrossthepreviouslychargedreferencecapacitor.Circuitrywithinthechipensuresthatthecapacitorwillbeconnectedwiththecorrectpolaritytocausetheintegratoroutputtoreturntozero.Thetimerequiredfortheout-puttoreturntozeroisproportionaltotheinputsignal.Specificallythedigitalreadingdisplayedis:

ZeroIntegratorPhase

Thefinalphaseiszerointegrator.First,inputlowisshortedtoanalogCOMMON.Second,afeedbackloopisclosedaroundthesystemtoinputhightocausetheintegratoroutputtoreturntozero.Undernormalcondition,thisphaselastsfrom100to200clockpulses,butafteranoverrangeconversion,itisextendedto6200clockpulses.

DifferentialInput

Theinputcanacceptdifferentialvoltagesanywherewithinthecommonmoderangeoftheinputamplifier;orspecificallyfrom0.5Vbelowthepositivesupplyto1Vabovethenegativesupply.InthisrangethesystemhasaCMRRof86dBtypical.However,sincetheintegratoralsoswingswiththecommonmodevoltage,caremustbeexercisedtoassuretheintegratoroutputdoesnotsaturate.Aworstcaseconditionwouldbealargepositivecommon-modevoltagewithanearfullscalenegativedifferentialinputvoltage.Thenegativeinputsignaldrivestheintegratorpositivewhenmostofitsswinghasbeenusedupbythepositivecommonmodevoltage.Forthesecriticalapplicationstheintegratorswingcanbereducedtolessthantherecommended4Vfullscaleswingwithsomelossofaccuracy.Theintegratoroutputcanswingwithin0.3Vofeithersupplywithoutlossoflinearity.

Analo