LCDLED显示AD转换器中英文资料外文翻译文献.docx

LCDLED显示AD转换器中英文资料外文翻译文献.docx

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LCDLED显示AD转换器中英文资料外文翻译文献

LCD/LED显示A/D转换器

中英文资料外文翻译文献

Digit,LCD/LEDDisplay,A/DConverters

Abstract:

TheIntersilICL7106andICL7107arehighperformance,lowpower,digitA/Dconverters.Includedaresevensegmentdecoders,displaydrivers,areference,andaclock.TheICL7106isdesignedtointerfacewithaliquidcrystaldisplay（LCD）andincludesamultiplexedbackplanedrive;theICL7107willdirectlydriveaninstrumentsizelightemittingdiode（LED）display.

TheICL7106andICL7107bringtogetheracombinationofhighaccuracy,versatility,andtrueeconomy.Itfeaturesautozerotolessthan10μV,zerodriftoflessthan1μV/℃,inputbiascurrentof10pA（Max）,androllovererroroflessthanonecount.Truedifferentialinputsandreferenceareusefulinallsystems,butgivethedesigneranuncommonadvantagewhenmeasuringloadcells,straingaugesandotherbridgetypetransducers.Finally,thetrueeconomyofsinglepowersupplyoperation（ICL7106）,enablesahighperformancepanelmetertobebuiltwiththeadditionofonly10passivecomponentsandadisplay.

Keyword:

DigitLCD/LEDDisplayA/DConverters

1Features

（1）GuaranteedZeroReadingfor0VInputonAllScales

（2）1pATypicalInputCurrent

（3）TrueDifferentialInputandReference,DirectDisplayDrive-LCDICL7106,LEDLCL7107

（4）LowNoise-LessThan15μVP-P

（5）OnChipClockandReference

（6）LowPowerDissipation-TypicallyLessThan10mW

（7）NoAdditionalActiveCircuitsRequired

2DetailedDescription

AnalogSection

Figure1showstheAnalogSectionfortheICL7106andICL7107.Eachmeasurementcycleisdividedintothreephases.Theyare

（1）auto-zero（A-Z）,

（2）signalintegrate（INT）and（3）de-integrate（DE）.

FIGURE1ANALOGSECTIONOFICL7106ANDICL7107

Auto-ZeroPhase

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

SignalIntegratePhase

Duringsignalintegrate,theauto-zeroloopisopened,theinternalshortisremoved,andtheinternalinputhighandlowareconnectedtotheexternalpins.TheconverterthenintegratesthedifferentialvoltagebetweenINHIandINLOforafixedtime.Thisdifferentialvoltagecanbewithinawidecommonmoderange:

upto1Vfromeithersupply.If,ontheotherhand,theinputsignalhasnoreturnwithrespecttotheconverterpowersupply,INLOcanbetiedtoanalogCOMMONtoestablishthecorrectcommonmodevoltage.Attheendofthisphase,thepolarityoftheintegratedsignalisdetermined.

De-IntegratePhase

Thefinalphaseisde-integrate,orreferenceintegrate.InputlowisinternallyconnectedtoanalogCOMMONandinputhighisconnectedacrossthepreviouslychargedreferencecapacitor.Circuitrywithinthechipensuresthatthecapacitorwillbeconnectedwiththecorrectpolaritytocausetheintegratoroutputtoreturntozero.Thetimerequiredfortheoutputtoreturntozeroisproportionaltotheinputsignal.Specificallythedigitalreadingdisplayedis:

DISPLAYCOUNT=

DifferentialInput

Theinputcanacceptdifferentialvoltagesanywherewithinthecommonmoderangeoftheinputamplifier,orspecificallyfrombelowthepositivesupplyto1Vabovethenegativesupply.Inthisrange,thesystemhasaCMRRof86dBtypical.However,caremustbeexercisedtoassuretheintegratoroutputdoesnotsaturate.Aworstcaseconditionwouldbealargepositivecommonmodevoltagewithanearfullscalenegativedifferentialinputvoltage.Thenegativeinputsignaldrivestheintegratorpositivewhenmostofitsswinghasbeenusedupbythepositivecommonmodevoltage.Forthesecriticalapplicationstheintegratoroutputswingcanbereducedtolessthantherecommended2Vfullscaleswingwithlittlelossofaccuracy.Theintegratoroutputcanswingtowithinofeithersupplywithoutlossoflinearity.

DifferentialReference

Thereferencevoltagecanbegeneratedanywherewithinthepowersupplyvoltageoftheconverter.Themainsourceofcommonmodeerrorisaroll-overvoltagecausedbythereferencecapacitorlosingorgainingchargetostraycapacityonitsnodes.Ifthereisalargecommonmodevoltage,thereferencecapacitorcangaincharge（increasevoltage）whencalleduptode-integrateapositivesignalbutlosecharge（decreasevoltage）whencalleduptode-integrateanegativeinputsignal.Thisdifferenceinreferenceforpositiveornegativeinputvoltagewillgivearoll-overerror.However,byselectingthereferencecapa