TPS63030中文资料(12)

元器件交易网SLVS696–

DETAILEDDESCRIPTION

CONTROLLERCIRCUIT

Thecontrollingcircuitofthedeviceisbasedonanaveragecurrentmodetopology.Theaverageinductorcurrentisregulatedbyafastcurrentregulatorloopwhichiscontrolledbyavoltagecontrolloop.Thecontrolleralsousesinputandoutputvoltagefeedforward.Changesofinputandoutputvoltagearemonitoredandimmediatelycanchangethedutycycleinthemodulatortoachieveafastresponsetothoseerrors.ThevoltageerroramplifiergetsitsfeedbackinputfromtheFBpin.Atadjustableoutputvoltagesaresistivevoltagedividermustbeconnectedtothatpin.AtfixedoutputvoltagesFBmustbeconnectedtotheoutputvoltagetodirectlysensethevoltage.Fixedoutputvoltageversionsuseatrimmedinternalresistivedivider.Thefeedbackvoltagewillbecomparedwiththeinternalreferencevoltagetogenerateastableandaccurateoutputvoltage.

Thecontrollercircuitalsosensestheaverageinputcurrentaswellasthepeakinputcurrent.Withthis,maximuminputpowercanbecontrolledaswellasthemaximumpeakcurrenttoachieveasafeandstableoperationunderallpossibleconditions.Tofinallyprotectthedevicefromoverheating,aninternaltemperaturesensorisimplemented.

SynchronousOperation

Thedeviceuses4internalN-channelMOSFETstomaintainsynchronouspowerconversionatallpossibleoperatingconditions.Thisenablesthedevicetokeephighefficiencyoverawideinputvoltageandoutputpowerrange.

Toavoidgroundshiftproblemsduetothehighcurrentsintheswitches,twoseparategroundpinsGNDandPGNDareused.ThereferenceforallcontrolfunctionsistheGNDpin.ThepowerswitchesareconnectedtoPGND.BothgroundsmustbeconnectedonthePCBatonlyonepointideallyclosetotheGNDpin.Duetothe4-switchtopology,theloadisalwaysdisconnectedfromtheinputduringshutdownoftheconverter.Buck-BoostOperation

Tobeabletoregulatetheoutputvoltageproperlyatallpossibleinputvoltageconditions,thedeviceautomaticallyswitchesfromstepdownoperationtoboostoperationandbackasrequiredbytheconfiguration.Italwaysusesoneactiveswitch,onerectifyingswitch,oneswitchpermanentlyon,andoneswitchpermanentlyoff.Therefore,itoperatesasastepdownconverter(buck)whentheinputvoltageishigherthantheoutputvoltage,andasaboostconverterwhentheinputvoltageislowerthantheoutputvoltage.Thereisnomodeofoperationinwhichall4switchesarepermanentlyswitching.Controllingtheswitchesthiswayallowstheconvertertomaintainhighefficiencyatthemostimportantpointofoperation;wheninputvoltageisclosetotheoutputvoltage.TheRMScurrentthroughtheswitchesandtheinductoriskeptataminimum,tominimizeswitchingandconductionlosses.Switchinglossesarealsokeptlowbyusingonlyoneactiveandonepassiveswitch.Regardingtheremaining2switches,oneiskeptpermanentlyonandtheotheriskeptpermanentlyoff,thuscausingnoswitchinglosses.

PowerSaveModeandSynchronization

ThePS/SYNCpincanbeusedtoselectdifferentoperationmodes.Toenablepowersave,PS/SYNCmustbesetlow.Powersavemodeisusedtoimproveefficiencyatlightload.Ifpowersavemodeisenabled,theconverterstopsoperatingiftheaverageinductorcurrentgetslowerthanabout100mAandtheoutputvoltageisatoraboveitsnominalvalue.Iftheoutputvoltagedecreasesbelowitsnominalvalue,thedevicerampsuptheoutputvoltageagainbystartingoperationusingaprogrammedaverageinductorcurrenthigherthanrequiredbythecurrentloadcondition.Operationcanlastforoneorseveralpulses.Theconverteragainstopsoperatingoncetheconditionsforstoppingoperationaremetagain.

ThepowersavemodecanbedisabledbyprogramminghighatthePS/SYNC.ConnectingaclocksignalatPS/SYNCforcesthedevicetosynchronizetotheconnectedclockfrequency.SynchronizationisdonebyaPLL,sosynchronizingtolowerandhigherfrequenciescomparedtotheinternalclockworkswithoutanyissues.ThePLLcanalsotoleratemissingclockpulseswithouttheconvertermalfunctioning.ThePS/SYNCinputsupportsstandardlogicthresholds.