TC7136TC9400 - 数显频率表

Twolow-costintegratedcircuitscanbecombinedtocreatea

simpledigitalfrequencymeter.Thecombinationofafrequency-to-

voltageconverter(FVC)andadual-slope,analog-to-digitaldisplay

converter(ADC)makesasmall2-chipfrequencymeterthatcanbe

runfromone9-voltbattery.

TheADC(TC7136)generatesthevoltagerequiredbytheFVC

(TC9400)withinternalregulators.TheTESToutputoftheTC7136

isregulatedto5voltsbelowthepositivebatteryterminal(V+)and

theANALOGCOMMONoutputisregulatedto3VbelowV+.The

TC7136isdesignedtodirectlydrivea3-1/2digit,non-multiplexed

LCDdisplaysonodigitalconversionisrequired.

ThetestvoltageisusedasthereferencesupplyfortheTC9400and

ANALOGCOMMONservesasthe"ground"forthecomparator

andtheintegratingamplifier.AN37TC7136/TC9400