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时间: 2019-12-27 21:05
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ThistechnicalbriefdescribesamicrocontrollerbasedSoft-StartControllercircuitforaswitchingpowersupply.Start-upisastressfultimeforthepowerdriversectionofaswitchingpowersupply.Becausetheoutputvoltageisinitiallyzero,thefeedbackerrorinitiallyjumpstoitsmaxi-mum.Thelargefeedbackerrorthendrivestheloopfiltertoitslimit,whichdrivesthepowerswitchingtransistorsinthedriversectionofthepowersupplyattheirmaximumrating.Thisconditioncontinuesuntiltheoutputvoltageofthepowersupplyapproachesitsnominalvalue.Iftheloadbeingdrivenbythepowersupplyiscapacitive,theproblemisexaggeratedduetothelargetransientcurrentsrequiredtochargethecapacitiveload.Inextremeinstances,therepeatedhighstressofstart-upcanresultincatastrophicfailuresinthedriversection,typically,thepowerMOSFETtransistorsorthepowerrectifiers.TB081Soft-StartControllerForSwitchingPowerSuppliesAuthors:JohnDayIMPLEMENTATIONKeithCurtisMicrochipTechnologyInc.HardwareOVERVIEWThehardwareforthesoft-startcircuitconsistsofthreecomponents;aPIC10F200microcontroller,a0.1uFThistechnicalbriefdescribesamicrocontrollerbasedcapacitoranda10kpull-downresistor.TherampingSoft-StartControllercircuitforaswitchingpowersupply.PWMfunctionisimplementede……