UC3825应用手册.pdf

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1、applicationUC1825INFOUC2825availableUC3825HighSpeedPWMControllerFEATURESDESCRIPTION·CompatiblewithVoltageorCurrentModeTheUC1825familyofPWMcontrolICsisoptimizedforhighfre-Topologiesquencyswitchedmodepowersupplyapplications.Particularcarewasgiventominimizingpropagationdela

2、ysthroughthecomparators·PracticalOperationSwitchingFrequenciesandlogiccircuitrywhilemaximizingbandwidthandslewrateoftheto1MHzerroramplifier.Thiscontrollerisdesignedforuseineithercur-·50nsPropagationDelaytoOutputrent-modeorvoltagemodesystemswiththecapabilityforinputvolt-a

3、gefeed-forward.·HighCurrentDualTotemPoleOutputs(1.5APeak)Protectioncircuitryincludesacurrentlimitcomparatorwitha1Vthreshold,aTTLcompatibleshutdownport,andasoftstartpin·WideBandwidthErrorAmplifierwhichwilldoubleasamaximumdutycycleclamp.Thelogicisfully·FullyLatchedLogicwit

4、hDoublePulselatchedtoprovidejitterfreeoperationandprohibitmultiplepulsesatSuppressionanoutput.Anunder-voltagelockoutsectionwith800mVofhysteresisassureslowstartupcurrent.Duringunder-voltagelockout,theout-·Pulse-by-PulseCurrentLimitingputsarehighimpedance.·SoftStart/Max.Du

5、tyCycleControlThesedevicesfeaturetotempoleoutputsdesignedtosourceand·Under-VoltageLockoutwithHysteresissinkhighpeakcurrentsfromcapacitiveloads,suchasthegateofapowerMOSFET.Theonstateisdesignedasahighlevel.·LowStartUpCurrent(1.1mA)BLOCKDIAGRAMUDG-92030-2SLUS235A-MARCH1997-

6、REVISEDMARCH2004UC1825UC2825UC3825ABSOLUTEMAXIMUMRATINGS(Note1)CONNECTIONDIAGRAMSSupplyVoltage(Pins13,15)........................30VDIL-16(TopView)OutputCurrent,SourceorSink(Pins11,14)DC...........................................0.5AJorNPackagePulse(0.5s)...............

7、....................2.0AAnalogInputs(Pins1,2,7)...............................-0.3Vto7V(Pin8,9).................................-0.3Vto6VClockOutputCurrent(Pin4).......................-5mAErrorAmplifierOutputCurrent(Pin3)................5mASoftStartSinkCurrent(Pin8).....

8、................20mAOscillatorChargingCurrent(Pin5)..................-5mAPowerDissipation..............