Marking, IDP2303 datasheet(21/38 Pages) INFINEON

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IDP2303

DigitalMulti-ModePFC+LLCComboController

Datasheet

Rev.V2.0,2017-03-21

3.5.3 LLCSmoothTransitionofFrequencyControlfromTCOtoVCO

Withbuilt-inHBLLCsoftstart,theoutputvoltagerisesupsmoothlyandfeedbackvoltageVHBFBisavailable

oncetheoutputvoltagereachesintheregulationrange.Duringthestartup,LLCleavesthesoftstartmode

andentersnormaloperationmodeiftheswitchingfrequencydeterminedbytheVCOisequaltoorhigher

thantheswitchingfrequencydeterminedbytheTCO,thenthevoltagecontrolledoscillator(VCO)takesover

thefrequencycontrol.

3.5.4 LLCHalf-bridgeProtection

TheLLChalf-bridgeisprotectedagainst:

•

LLCOpenControlLoopProtection(LLCOCLP)(Chapter3.5.4.1)

•

LLCOverLoadProtection(LLCOLP)(Chapter3.5.4.2)

•

LLCOverCurrentProtection1(LLCOCP1)(Chapter3.5.4.3)

•

LLCOverCurrentProtection2(LLCOCP2)(Chapter3.5.4.4)

Inthiscontroller,theHBLLCconverterisprotectedagainstHBopenloopandoverload(OLP),overcurrent

3.5.4.1 LLCOpenControlLoopProtection(LLCOCLP)

Opencontrolloopmayhappenduetoopencircuitinopto-couplereitheratthediodeoratthetransistor,

opencircuitinHBfeedbackpinorthebrokenconnectionoftheICpintotheopto-couplertransistorsource

terminal.Inthiscase,theHBfeedbackVHBFBstaysathigh.Aftertheendofthesoftstart,theaveragedvalueof

thefeedbackvoltageVHBFBovertimeperiodofN_AccHB*t_SrHBiscomparedwiththethresholdV_OlpHB.Ifthe

measuredvalueishigherthanthethresholdfortimet_OlpHB,thentheopenloopprotectionistriggeredand

thewholesystementersauto-restartmode.Thesystemwillbestoppedandatimebreakt_ARfollows.After

thistimebreak,theHBLLCconverterrestartsagainwithsoftstart.Thisisopenloopprotection.

3.5.4.2 LLCOverLoadProtection(LLCOLP)

OverloadattheHBLLCoutputduringnormaloperationleadstoriseofthefeedbackvoltageVHBFB.Oncethe

averagedvalueofthefeedbackvoltageVHBFBovertimeperiodofN_AccHB*t_SrHBishighthanthethreshold

V_OlpHBfortimet_OlpHB,theoverloadprotectionistriggeredandtheHBcontroller,togetherwithPFC,enters

auto-restartmode.TheHBLLCconverterwillbestoppedandatimebreakt_ARfollows.Afterthistimebreak,

theHBLLCconverterrestartsagainwithsoftstart.

3.5.4.3 LLCOverCurrentProtectionLevel1(LLCOCP1)

LLCOCP1isimplementedwithhardwarecomparatorandfirmwarehandlingandtheconditionischeckedat

everyLLCswitching.ThevoltageacrosstheshuntresistorRHBatthelow-sideMOSFETissensedviatheCS1

pin.TherearethreedifferentovercurrentprotectionthresholdsV_Ocp1_norm,V_Ocp1_burstandV_Ocp1_startuptocover

variousoperationconditions.ThethresholdV_Ocp1_startupisappliedduringstartup,thethresholdV_Ocp1_burstis

appliedduringleavingburstmodetransitiontoavoidtheOCP1mis-triggeredandtherelativelylower

thresholdV_Ocp1_normisappliedduringnormaloperation.

IfthevoltageacrosstheshuntresistorRHBatthelow-sideMOSFETexceedstheOCP1threshold,OCP1

protectionistriggeredtoincreasethecurrentswitchingfrequencytatrateoft_Slope_afterOCP1tolimitthe

power.ThehigherswitchingfrequencyresultsinreducedcurrentflowingintheLLCtankandlimitsthe

outputpowertransfer.IfthesensedcurrentfallsbelowtheOCPthreshold,theLLCswitchingfrequency

startstobereduced.AtthepointwherethecalculatedLLCswitchingfrequencybasedontheHBFBsignalis

higherthantheswitchingfrequencyasdefinedbytheOCP1protection,theLLCconverterresumescontrol

underVCO.

IfabovescenariooccurscontinuouslymorethanN_Ocp1_maxtimes,thentherewillbeaseriousfaultcondition,

ICwillenterautorestartprotectionmodetoprotectthewholesystem.Inthemeantime,duetothelimited

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