位AD转换器中英文翻译资料.doc

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1、英文原文12-BitA/DConverterCIRCUITOPERATIONTheAD574Aisacomplete12-bitA/Dconverterwhichrequiresnoexternalcomponentstoprovidethecompletesuccessiveapproximationanalog-to-digitalconversionfunction.AblockdiagramoftheAD574AisshowninFigure1.Figure1.BlockDiagramofAD574A12-Bi

2、tA-to-DConverterWhenthecontrolsectioniscommandedtoinitiateaconversion(asdescribedlater),itenablestheclockandresetsthesuccessiveapproximationregister(SAR)toallzeros.Onceaconversioncyclehasbegun,itcannotbestoppedorrestartedanddataisnotavailablefromtheoutputbuffers

3、.TheSAR,timedbytheclock,willsequencethroughtheconversioncycleandreturnanend-of-convertflagtothecontrolsection.Thecontrolsectionwillthendisabletheclock,bringtheoutputstatusflaglow,andenablecontrolfunctionstoallowdatareadfunctionsbyexternalcommand.Duringtheconvers

4、ioncycle,theinternal12-bitcurrentoutputDACissequencedbytheSARfromthemostsignificantbit(MSB)toleastsignificantbit(LSB)toprovideanoutputcurrent20/21whichaccuratelybalancestheinputsignalcurrentthroughthe5kΩ(or10kΩ)inputresistor.Thecomparatordetermineswhethertheaddi

5、tionofeachsuccessively-weightedbitcurrentcausestheDACcurrentsumtobegreaterorlessthantheinputcurrent。ifthesumisless,thebitislefton。ifmore,thebitisturnedoff.Aftertestingallthebits,theSARcontainsa12-bitbinarycodewhichaccuratelyrepresentstheinputsignaltowithin1/2LSB

6、.Thetemperature-compensatedburiedZenerreferenceprovidestheprimaryvoltagereferencetotheDACandguaranteesexcellentstabilitywithbothtimeandtemperature.Thereferenceistrimmedto10.00volts±0.2%。itcansupplyupto1.5mAtoanexternalloadinadditiontotherequirementsofthereferenc

7、einputresistor(0.5mA)andbipolaroffsetresistor(1mA)whentheAD574Aispoweredfrom±15Vsupplies.IftheAD574Aisusedwith±12Vsupplies,orifexternalcurrentmustbesuppliedoverthefulltemperaturerange,anexternalbufferamplifierisrecommended.AnyexternalloadontheAD574Areferencemust

8、remainconstantduringconversion.Thethin-filmapplicationresistorsaretrimmedtomatchthefull-scaleoutputcurrentoftheDAC.Therearetwo5kWinputscalingresistorstoalloweithera10