一个简单的微控制器驱动电路的PWM发生器

Therecentinterestinintelligentpowersupplieshas

driventhedevelopmentofanewclassofmicrocontrol-

lerfriendlyPWMgenerators.ThesePWMgenerators

arethemixedsignalcontrolblocksforSwitchmode

powersupplies.OnesuchdeviceistheMCP1630.The

MCP1630containsthe3mainelementsfordesigning

aswitchingpowersupplyasaperipheraltoamicrocon-

troller:aset/resetflip-flop,ahigh-speedvoltage

comparatorandanopamptoimplementtheerror

amplifier(seeFigure1).

ThemicrocontrollercontrolstheMCP1630throughits

clockinput.Thefrequencyoftheclockdeterminesthe

pulsefrequencyofthePWMoutput,andthedutycycle

oftheclocklimitsthemaximumPWMdutycycleofthe

output.Controlofthedutycyclebetween0andthe

maximumsetbytheclockinputisdeterminedbythe

currentfeedbacktothecomparatorandtheoutputof

theerroramplifier(seeFigure2).TB085ASimpleCircuitforDrivingMicrocontrollerFriendlyPWMGeneratorsBecausetheMCP1630doesnotcontainanon-chipAuthor:KeithCurtisMicrochipTechnologyInc.oscillator,itsapplicationinnon-intelligentordumbpowersupplydesigns,islimited.However,marryingtheMCP1630withasmallpin-countmicrocontrollerINTRODUCTIONsolvestheoscillatorpro