标签: slyt096

slyt096PowerManagementTexasInstrumentsIncorporatedSoft-startcircuitsforLDOlinearregulatorsByJeffFalin(Email:j-falin1@ti.com)Applications,PortablePowerManylow-dropout(LDO)linearregulatorsdonothaveanintegrated“soft-start”functionthatlimitsthein-rushcurrenttothedevicebeingpowered.Infact,asthesimplifiedblockdiagraminFigure1shows,mostlinearregulatorsconsistofonlyareference,anerroramplifier,andapasselement.Thus,atstartup,theerroramplifiersensesthattheoutputvoltageislowanddrivesthepasselementashardaspossible.Thepasselementpullsalargein-rushcurrenttochargetheoutputcapacitanceand/orloadcurrentabruptly,afterashortdelay.Thedelayiscausedbythreefactors:thetimerequiredfortheinputvoltage……