TPS63030中文资料(13)

元器件交易网

SLVS696–OCTOBER2008

DeviceEnable

ThedeviceisputintooperationwhenENissethigh.ItisputintoashutdownmodewhenENissettoGND.Inshutdownmode,theregulatorstopsswitching,allinternalcontrolcircuitryisswitchedoff,andtheloadisdisconnectedfromtheinput.Thisalsomeansthattheoutputvoltagecandropbelowtheinputvoltageduringshutdown.Duringstart-upoftheconverter,thedutycycleandthepeakcurrentarelimitedinordertoavoidhighpeakcurrentsflowingfromtheinput.SoftstartandShortCircuitProtection

Afterbeingenabled,thedevicestartsoperating.Theaveragecurrentlimitrampsupfromaninitial400mAfollowingtheoutputvoltageincreasing.Atanoutputvoltageofabout1.2V,thecurrentlimitisatitsnominalvalue.Iftheoutputvoltagedoesnotincrease,thecurrentlimitwillnotincrease.Thereisnotimerimplemented.Thustheoutputvoltageovershootatstartup,aswellastheinrushcurrent,iskeptataminimum.Thedevicerampsuptheoutputvoltageinacontrolledmannerevenifaverylargecapacitorisconnectedattheoutput.Whentheoutputvoltagedoesnotincreaseabove1.2V,thedeviceassumesashortcircuitattheoutputandkeepsthecurrentlimitlowtoprotectitselfandtheapplication.Atashortattheoutputduringoperationthecurrentlimitalsowillbedecreasedaccordingly.At0Vattheoutput,forexample,theoutputcurrentwillnotexceedabout400mA.UndervoltageLockout

Anundervoltagelockoutfunctionpreventsdevicestart-upifthesupplyvoltageonVINAislowerthanapproximatelyitsthreshold(seeelectricalcharacteristicstable).Wheninoperation,thedeviceautomaticallyenterstheshutdownmodeifthevoltageonVINAdropsbelowtheundervoltagelockoutthreshold.Thedeviceautomaticallyrestartsiftheinputvoltagerecoverstotheminimumoperatinginputvoltage.OvertemperatureProtection

Thedevicehasabuilt-intemperaturesensorwhichmonitorstheinternalICtemperature.Ifthetemperatureexceedstheprogrammedthreshold(seeelectricalcharacteristicstable)thedevicestopsoperating.AssoonastheICtemperaturehasdecreasedbelowtheprogrammedthreshold,itstartsoperatingagain.Thereisabuilt-inhysteresistoavoidunstableoperationatICtemperaturesattheovertemperaturethreshold.