热敏电阻在单电源的温度传感电路

INTRODUCTION

Thereisavarietyoftemperaturesensorsonthemarket

allofwhichmeetspecificapplicationneeds.Themost

commonsensorsthatareusedtosolvetheseapplica-

tionproblemsincludethethermocouple,Resistive

TemperatureDetector(RTD)thermistor,andsili-

con-basedsensors.Foranoverviewandcomparison

ofthesesensors,refertoMicrochip’sAN679,“Temper-

atureSensingTechnologies”.

Thisapplicationnotefocusesoncircuitsolutionsthat

useNegativeTemperatureCoefficient(NTC)ther-

mistorsinthedesign.TheThermistorhasanon-linear

resistancechange-overtemperature.Thedegreeof

thisnon-linearitywillbediscussedinthe“Hardware

LinearizationSolutions”sectionofthisapplicationnote.

Fromthisdiscussion,variouslinearizationresistornet-

workswillbeshownwitherroranalysisincluded.

Finally,thesignalconditioningpathforthethermistor

systemwillbecoveredwithcompleteapplicationcir-

cuitsfromsensorormicroprocessor.AN685ThermistorsinSingleSupplyTemperatureSensingCircuitsgeneratedbythepowerdissipatedbytheelement.AnyAuthor:BonnieC.BakerchangeintheflowoftheliquidorgasacrossthedeviceMicrochipTechnologyInc.changesthepowerdissipationfactorofthethermistorelement.Inthismanner,theresistanceofthether-INTRODUCTIONmistorischanged,relat