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PWMCONTROL
OVERCURRENTPROTECTION
THERMALSHUTDOWN
电源-好的(pwrgd)
dead-timecontrolamdmosfet
TPS54010
SLVS509–MAY2004
thehigh-sideandlow-sidedriversaredesignedwith
300-masourceandsinkcapabilitytoquicklydrivethe
signalsfromtheerroramplifieroutput,振荡器,和
powermosfetsgates.thelow-sidedriverissup-
currentlimitcircuitareprocessedbythePWMcontrol
pliedfromvin,whilethehigh-sidedriveissupplied
逻辑.referringtotheinternalblockdiagram,这
fromthebootpin.abootstrapcircuitusesan
controllogicincludesthepwmcomparator,orgate,
externalbootcapacitorandaninternal2.5-
Ω
pwmlatch,andportionsoftheadaptivedead-时间
bootstrapswitchconnectedbetweentheVINand
andcontrol-logicblock.duringsteady-stateoperation
bootpins.theintegratedbootstrapswitchimproves
belowthecurrentlimitthreshold,thepwm
driveefficiencyandreducesexternalcomponent
comparatoroutputandoscillatorpulsetrainalter-
计数.
natelyresetandsetthepwmlatch.oncethepwm
latchisset,thelow-sidefetremainsonfora
minimumdurationsetbytheoscillatorpulsewidth.
duringthisperiod,thepwmrampdischargesrapidly
thecycle-用-cyclecurrentlimitingisachievedby
toitsvalleyvoltage.whentherampbeginstocharge
sensingthecurrentflowingthroughthehigh-一侧
backup,thelow-sidefetturnsoffandhigh-一侧
MOSFETandcomparingthissignaltoapreset
fetturnson.asthepwmrampvoltageexceedsthe
overcurrentthreshold.thehighsidemosfetis
erroramplifieroutputvoltage,thepwmcomparator
turnedoffwithin200nsofreachingthecurrentlimit
resetsthelatch,thusturningoffthehigh-sidefet
门槛.a100-nsleadingedgeblankingcircuit
andturningonthelow-sidefet.thelow-sidefet
preventscurrentlimitfalsetripping.currentlimit
remainsonuntilthenextoscillatorpulsedischarges
detectionoccursonlywhencurrentflowsfromVINto
thepwmramp.duringtransientconditions,theerror
phwhensourcingcurrenttotheoutputfilter.加载
amplifieroutputcouldbebelowthePWMrampvalley
protectionduringcurrentsinkoperationisprovidedby
voltageorabovethepwmpeakvoltage.iftheerror
thermalshutdown.
amplifierishigh,thepwmlatchisneverreset,和
thehigh-sidefetremainsonuntiltheoscillatorpulse
signalsthecontrollogictoturnthehigh-sidefetoff
Thedeviceusesthethermalshutdowntoturnoffthe
andthelow-sidefeton.thedeviceoperatesatits
powerMOSFETsanddisablethecontrollerifthe
maximumdutycycleuntiltheoutputvoltagerisesto
junctiontemperatureexceeds150
°
c.thedeviceis
theregulationset-要点,settingvsensetoapproxi-
releasedfromshutdownautomaticallywhenthejunc-
matelythesamevoltageasvref.iftheerror
tiontemperaturedecreasesto10
°
cbelowthether-
amplifieroutputislow,thepwmlatchiscontinually
malshutdowntrippoint,andstartsupundercontrol
resetandthehigh-sidefetdoesnotturnon.这
oftheslow-startcircuit.
低-sidefetremainsonuntilthevsensevoltage
decreasestoarangethatallowsthePWM
thermalshutdownprovidesprotectionwhenanover-
comparatortochangestates.thetps54010is
loadconditionissustainedforseveralmilliseconds.
capableofsinkingcurrentcontinuouslyuntilthe
withapersistentfaultcondition,thedevicecycles
outputreachestheregulationset-要点.
continuously;startingupbycontroloftheslow-开始
电路,heatingupduetothefaultcondition,andthen
Ifthecurrentlimitcomparatortripsforlongerthan
shuttingdownuponreachingthethermalshutdown
100ns,thepwmlatchresetsbeforethepwmramp
trippoint.thissequencerepeatsuntilthefault
exceedstheerroramplifieroutput.thehigh-sidefet
conditionisremoved.
turnsoffandlow-sidefetturnsontodecreasethe
energyintheoutputinductorandconsequentlythe
outputcurrent.thisprocessisrepeatedeachcyclein
whichthecurrentlimitcomparatoristripped.
Thepowergoodcircuitmonitorsforundervoltage
conditionsonvsense.ifthevoltageonvsenseis
10%belowthereferencevoltage,theopen-流
驱动器
pwrgdoutputispulledlow.pwrgdisalsopulled
lowifvinislessthantheuvlothresholdorss/ena
adaptivedead-timecontrolpreventsshoot-通过
islow.whenvin.uvlothreshold,ss/ena.使能
currentfromflowinginbothn-channelpower
门槛,andvsense>90%ofvref,theopen
MOSFETsduringtheswitchingtransitionsbyactively
drainoutputofthepwrgdpinishigh.ahysteresis
controllingtheturn-ontimesofthemosfetdrivers.
voltageequalto3%ofV
ref
anda35-µsfallingedge
thehigh-sidedriverdoesnotturnonuntilthevoltage
deglitchcircuitpreventtrippingofthepowergood
atthegateofthelow-sidefetisbelow2v.当
comparatorduetohighfrequencynoise.
thelow-sidedriverdoesnotturnonuntilthevoltage
atthegateofthehigh-sidemosfetisbelow2v.
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