switch\Ac To DC 5V3A

AN1231-APPLICATIONNOTEVIPower:VIPer50FORUSBSELF-POWEREDHUBA.Bailly-F.Grilli1SCOPETheworkingfrequencyhasbeensettoaboutΩThisdocumentpresentstheresultsobtainedfrom50KHz(47.6KHz)usingR1=5.1KandaUSBoff-linepowersupplydesignedwithC5=8.2nF.VIPer50.ThepotentiometerP1couldberemoved,ifoutputThisdesignisacompletesolutionforpoweringadjustmentisnotnecessarytocompensateSelf-powered4-portshubs.voltagedropsonthefollowingstages(mainlyonPowerDistributors).ItsuppliestheUSBHUB-controllerbydeliveringupto15W(thisismorethanenoughtomeettheByremovingP1thevalueofR8becomestheUSBrequirements),500mAeachport.InthecasesameofR7(4K7)andashort-circuitmustbethata3.3Visneeded,avoltageregulatorcanbeplacedbetweentheendsofP1.added.3.0MEASUREMENTS2SCHEMATICUnlessotherwisenoted,allmeasurementshaveTheUSBpowersupplyisbasedonthestandardbeenmadewithahighvoltageDCsource,schematicRCD-snubber-TL431suggestedintherangingfrom100Vto400V.ThiscorrespondstoVIPersoftware.anACinputvoltagefrom85Vac(consideringtheThecompleteschematicisshowninfigure1.voltagerippleofthebulkcapacitor)to280Vac.Thiscircuitoperatesfrom85Vacto275Vac,withanoutputcurrent,on5V,varyingfrom20mAto3A.Figure1:SchematicdiagramD22362.5003AR45ELDOR726.81N4148D14DF06720M6312R3L2C656K10D6+5V33n2u7630V4STPS1045C3C10C29C11C1247u1000u150nSTTA1061470u470u275V~400VD316V25V25VTR2R12IC13TR15K1VIPer50L12X56mHVDDC41DRAINOSCC147u220n275V~C5COMPSOURCR58n233054R7F1R62AT61K4K7R221ISO1D43K9TCDT1101GP1CON13V3C72K21/2W45210u47UniversalMains90-275VacD5C910nR83K3C8TL4314n7/3KVJanuary20001/151AN1231-APPLICATIONNOTE3.1EFFICIENCYThebehaviourofthepreviouscurvesgivestheideathattheswitchinglossesarepreponderantFigure2givesthesystemefficiencymeasuredfordifferentoutputcurrentsat4differentvaluesofversusconductionlossesataverylowoutputinputvoltage.Figure3reportsindetailthecurrent.efficiencyforlowoutputcurrentupto150mA.Usingthemathematiccapabilityofscope,itispossibletomakeanestimationofpowerlosses.Figure2:EfficiencyThemeasureshavebeendoneat400Vdcandfull90load:80Turnonlosses:70µPON=3.92J·47.6KHz=0.186W6050Figure4:Turnonlosses%403020100Vdc300Vdc200Vdc400Vdc10000.511.522.53OutputCurrent(A)Figure3:Efficiencyatlowcurrent706050Turnofflosses:40µPOFF=5.60J·47.6Hz=0.266W%30Figure5:Turnofflosses20100Vdc300Vdc10200Vdc400Vdc00102030405060708090100110120130140150OutputCurrent(mA)Table1:NumericalValuesEfficiencyEfficiencyEfficiencyInputVoltageat20mAat1.5Aat3A100V22%75%74%200V18%77%77%300V16%76%77%Notethattherightcursorhasbeensetatabout400V15%74%77%thesamevalueastheturnonvoltage.2/15AN1231-APPLICATIONNOTEThisassumesthatnothingisdissipatedatturnoff,temperatureof70°Candathermalresistanceofbecausethecrossovertimeisonlyduetocharge60°C/WinfreeairtheVIPercanworkwithoutany°ofthedraincapacitanceandtheinternalturnoffofheatsink(Tjmax=120C),whileforthediodetheheatsinkisrequired.thepowerMOSFETissufficientlyfast.Thecorre-spondingenergyofthiscapacitorisdissipatedat3.2BURSTMODEturnon,andthisexplainsthatonlythepartofvolt-Whentheoutputcurrentistoolow,theminimumagewhichisdischargedatturnonistakenintoduty-cyclefixedbytheinternalblankingtimeofaccountatturnoff.thedeviceistoohightocontroltheoutputvoltage.TheconductionlossescanbeestimatedasInsuchacase,theburstmodeoperationtakesfollows:placeautomatically,thankstotheVIPer50ability2PCD=tON/tSW·Rdson·Ip/3=0.146WtomaintainitspowerswitchintheoffstatewhenthevoltageonthecompensationpingoesbelowAlsothepowerdissipatedbysignalpartand0.5V.biasingresistorhavetobeconsidered(refertoAN947foradeeperanalysis)inordertohavetheFigure6:GoodburstmodecompletepowerdissipatedbyVIPer50Table2.VIPer50PowerDissipationParameterValuePON0.186WPOFF0.266WPCD0.146WPbias0.140WPdd0.120WPtot0.858WThemeasuredcasetemperaturewas70.5°Cforanambienttemperatureof23°C.Thiscorrespondtoadissipatedpowerofabout0.8Wwithather-malresistanceof60°C/W(freeair,noheatsink)wellinaccordancewiththeabovecalculatedlosses.TheSTPS1045conductionpowerlosseswerecalculatedusingtheformulareportedontheThisresultsinmissingcycles,asshownonthedatasheet:scopewaveformsreportedinfigure62(Vin=400Vdc,Iout=30mA).P=0.42·IF(AV)+0.015·IF(RMS)=1.53WTheburstmodehasarecurringperiodofabout400µs,and8switchingcyclestakeplaceeachwhere,inthecaseoftriangularwaveform:time.Theoutputrippleisabout10mVandtheVddvoltageisstable,justabovethelowthresholdvolt-I=I·δ/2F(AV)Mage(8V)oftheinternalUVLOlogic.Thisthresh-oldcanbereachedbyfurtherreducingtheoutput22δIF(RMS)=IM·/3current,becauseitalsoreducestheVddvoltageontheprimaryside(lessandlessenergyfromtheThepowerlossesinthediodearedoublethanauxiliarywinding).Whenthisoccurs,anothertypethoseintheVIPer50.Consideringanambientofburstmodeappears,whichiscontrolledbythe3/15AN1231-APPLICATIONNOTEVddvoltage.Thisiscalledthe“bad”burstmode.Inconclusion,thegoodburstmodehastobeThefollowingscopewaveformsshowwhathap-extendedinthelowoutputpowerrangeasmuchpensinthiscase(Vin=400Vdc,Iout=10mA).aspossible,mainlyoptimizingthetransformer.ThebadburstmodeoccupiesaverylowrangeofFigure7:Badburstmodeoutputcurrent,inwhichthepowersupplydoesn’thaveitsnominalperformance.Buttheoutputvolt-ageisstillundercontrol(nooverpassingthenom-inalvoltage),andnostressisappliedtothepowersupply.3.3.LOADREGULATION3.3.1.STATICREGULATIONFigure8showstheoutputregulationforanoutputcurrentrangingfrom20mAto3A.Thefourcurveshavebeendoneatdifferentinputvoltages.Figure8:Staticloadregulation5.02EachtimethattheVddvoltagereachesthelow5.01thresholdvoltageoftheUVLOlogicthedeviceisresetandtheVddcapacitorischargedbacktothe5highthresholdoftheUVLOlogicthankstothestartupcurrentsourcethatisturnedon.The4.99recurringperiodofthisphenomenonisabout60ms.Thisbehaviorleadstothefollowingdraw-OutputVoltage(V)4.98backs:1.Sincethestartupcurrentsourceisactivated4.97100Vdc300Vdctosupplythedevicefromthehighvoltage200Vdc400Vdcrail,theefficiencydecreasesdramatically.4.960.020.200.400.600.801.001.201.401.601.802.002.202.402.602.803.00OutputCurrent(A)2.Therecurringperiodisveryhigh,leadingtoalargeoutputripple.Intheaboveexample,thisrippleisabout700mV,whichisnotacceptableforanoutputvoltageof5V.Thevoltagedropsfrom20mAto3Aisabout3.Thismodehasverypoordynamicbehavior50mV,thisismainlyduetotheresistanceoftheinthecaseofoutputcurrentvariation.Ifaninductance(~20mΩ)usedintheoutputfilter.increaseofoutputcurrentoccursduringtheConnectingtheresistivebridgeonTL431aftertherechargingphase,theoutputcapacitorwilloutputinductorthe50mVdropinloadregulationbedischargeddownto0Vandthenormalwillbeavoided.Weprefertoleavethefeedbackoutputvoltagewillreturnonlyatthenextconnectedafterthediode,becauseinsomerealstartingphase.applicationstheinductanceisnotpresent,orthe4/15AN1231-APPLICATIONNOTELCfilter(L2,C12)issplitanddedicatedforeach3.3.2.DYNAMICREGULATIONdownstreamport.Theoutputcurrenthasbeenmodulatedbyasquarewave,fromminimumload(20mA)tofullFigure9:Dynamicbehaviourfor0.66%toload(3A),fromminimumloadto50%,andfrom100%offullload50%tofullloadwithaninputvoltageof300Vdc.Figure11:Dynamicbehaviorfor100%to0.66%offullloadFigure10:Dynamicbehaviorfor0.66%to100%offullloadFigure12:Dynamicbehaviorfor0.66%to50%offullload5/15AN1231-APPLICATIONNOTEFigure13:Dynamicbehaviorfor50%to100%Thankstotheexcellentinputvoltagedisturbancesoffullloadrejectionofthedevice,the100Hzoutputrippleis2.6mVagainstthe33Vrippleonthebulkcapaci-tor(-82dB).Theinternalcurrentcontrollooptakescareofagoodpartoftheinputvoltagevariation,andtheoutervoltageloopmakesthefinalimprovements,thusreducingtheoutputvoltagevariationtosuchlevels.Figure15showstheswitchingnoise,at47.6KHz,ontheoutput.Thewaveformisrelatedto220Vacandanoutputcurrentof3A.Figure15:SwitchingNoise3.4.LINEREGULATION&SWITCHINGNOISEThepowersupplyhasbeenconnectedto85Vac/50Hzmainlines(worstcase,notevenreal)tomeasurethelinerejectionontheoutput.Boththeinputvoltageandtheoutputvoltagearereportedinfigure14,withafullloadoperation.Figure14:DynamicLineRegulationat100Hz3.5.TURNONTheinputvoltageof300Vdchassuddenlybeenappliedtothepowersupply,andtheoutputvoltagemonitoredfordifferentloadconditions.Theresultsarereportedinfigure16.ThestartingslopeisduetothevalueofC7whichdefinesthesoftstarttimeofthepowersupply.Thistimecanbeadjustedbychoosingthevalueofthiscapacitor,buttakecarethatthiscapacitorenteralsointheloopcalculation.ThevalueofC4mustbechangedaccordinglyinordertomaintaintheVddvoltageatasufficientlevelduringthissoftstarttime.6/15AN1231-APPLICATIONNOTEFigure16:StartupwaveformsFigure18:StartuptimeatdifferentVin3.6.TURNOFFThestartuptimehasalsobeenmeasuredusingThebehaviorofthepowersupplyatturnoffismains.Thisisgiveninfigure17,whereallthereportedinfigures19and20,forboththeoutputinput,Vddandoutputvoltagesaregivenatstartandinputvoltages.Itcanbeseenthattheoutputup,forafullloadcondition.Differentinputvoltagevoltagedecreasesinamonotoneway,withnodoesnotaffectthestartuptime,becauseitisduerestartafteritreachesthezerolevel.toaninternalcurrentgeneratorthatchargesC4.ThedevicestartstoworkwhentheVddreaches11V,asshowninfigure18for85Vacand275Vac.Figure19:Turnoffat20mAloadFigure17:Startuptime7/15AN1231-APPLICATIONNOTEFigure20:Turnoffat3AloadFigure22:Normaloperation85Vac,3A3.7.NORMALOPERATIONFigure23:Normaloperation275Vac,20mAThefollowingfiguresshowthevoltageandcurrentontheDrainpinatdifferentworkingconditions.With85Vacastheinputvoltageand3Aastheload,thepowersupplyisatthelimitofcontinuousmode,butthisisnotaproblemfortheIC.Figure21:Normaloperation85Vac,20mA8/15AN1231-APPLICATIONNOTEFigure24:Normaloperation275Vac,20mAFigure26:Overload5.554.543.53OutputVoltage(V)2.5100Vdc300Vdc200Vdc400Vdc21.52.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.25.45.65.86.0OutputCurrent(A)Figure25:Normaloperation275Vac,3ATheoutputvoltageat100Vdcdecreasesquicklybecausethesystemisincontinuousmode.4.IMPROVEMENTSSomemodificationshavebeendoneonthedesignofFigure1inordertoimprovethebehaviorofthepowersupply.Inarealapplicationwheretherearesomeprotectiondevicesbetweentheoutputofthepowersupplyandthedownstreamports,useraccessible,ashortcircuitwillneverbeseenbythepowersupply,unlessthishappenduetoafailureoftheUSBHubcontrolcircuit/device.4.1.SHORTCIRCUITBEHAVIORWith400Vdcinputvoltage,ashortcircuithasbeenmadeontheoutputofthepowersupply.Thisresultsinapermanentaveragecurrentof3.8.OVERLOADabout11A,wellabovethetransformercapability.WhentheoutputcurrentexceedsacertainvalueFigure27and28showIoutandIdiodeinthiscondition.theVddreaches13V,theVIPer50automaticallypassesintoprimarymoderegulation.InthecaseTheVIPer50iscontrolledonlybyThermalthattheoverloadincreasestogetherwithlimitingProtection,whentheinternaltemperatureovercomestheTtds(seethedatasheet)thethecurrentflowinginsidetheICbythezenerdiodeontheComppin,theoutputvoltagedevicestopsworking.decreasestomaintainVddat13V.9/15AN1231-APPLICATIONNOTEFigure27:VddandIoutinshortcircuitFigure29:Vdd,VauxinnormaloperationFigure28:VddandIdiodeinshortcircuitFigure30:Vdd,VauxinshortcircuitTheprotectionwhichisforeseenfortheVIPer50ThisspikeissufficienttomaintainacorrectsupplyconsistsofthemonitoringoftheVddvoltageandvoltagetothedevice,andeventoincreaseitstheswitchingoffofthedevicewhenthisvoltageisvoltageuptotheinternalreference(13V)wherebelowthelowthresholdvoltage(8V)oftheUVLOthedevicedecreasesthepeakcurrent.Actuallylogic.Thisisdonenaturallywhentheoutputvolt-thedeviceisregulatingitsprimaryVddvoltageageislow(i.e.inshortcircuit),becausetheauxil-throughtheauxiliarywindingspike.iarywindingisdeliveringaVddvoltagewhichisAsolutiontogetridofthesespikesistoimple-proportionaltotheoutputvoltage.mentafilterjustbyincreasingR4.ButthisleadsUnfortunately,thetransformerdeliverssomevolt-topoorperformancesinregulation,especiallyforagespikesatswitchoffontheauxiliarywinding,lightloads,wherethebadburstmodewillappearasshowninfigure29and30.forahigheroutputcurrentthannow.10/15AN1231-APPLICATIONNOTEAnothersolutionconsistsofusinganactiveswitchFigure33:Vdd,VauxandVaux’inshortcircuitinsteadoftheR4.Figure31presentsapossibleschematicwiththeadditionoftwomorecomponents,comparedwiththeformerone.Figure31.PossibleshortcircuitprotectionD22362.5003AD22362.5003ABC3275ELDOR5ELDORR46.8771N41481N4148470p446622K2210109911TR2TR2NotethatR4wasdoingthesamething,butinalessefficientway.Innormalmode,thisresistoravoidsexcessiveVddvoltage,whichshouldreachtheinternalreferencevoltage(13V)andinterfereswiththesecondaryfeedback.Withnewdesign,itAbipolartransistorisinsertedinserieswiththeispossibletoeliminatethisresistor,andeventoauxiliarywindinganditisdriventhroughanRCaddacoupleofturnsontheauxiliarywinding.network.TheRCdelaysthetransistorturnonAsaresult,theshortcircuitcurrentisnomorelim-whentheauxiliarywindingbeginstodeliverposi-itedbytheVddvoltageanditincreasesbecausetivevoltage,thusskippingthefirstspikes,astheVIPer50isinternallylimitedto2A,whichisshowninthefollowingfigures.doubleofwhatneededforfullload.TheZenerTherefore,theVddismorerepresentativeofwhatdiodeD4actsasclamperlimitingthemaxpeakhappensonthesecondaryside.currenttoamorereasonablelevel(about1.25A),thisavoidsthetransformercoresaturationalsoFigure32:Vdd,VauxandVaux’innormalduringthestartup.operationFigure34givestheoutputshortcircuitcurrent,usingtheabovementionedcircuittheaverageoutputcurrentisabout2A.Thiscurrentismoreacceptablethanthepreviousone,anditappearsthattheconverterisabletowithstandindefinitelytheshortcircuitcondition.11/15AN1231-APPLICATIONNOTEFigure34:VddandIoutinshortcircuitwithimprovements5.CONCLUSIONItappearsthattheVIPer50iswellsuitedforsuchapplicationsinwhichtheoutputpowerrangesfromhundredsofmilliWattstoafewdozenofWatts.Themostinterestingpointsare:1.Theautomaticburstmodewhichisimple-mentedthroughaninternalcomparatoronthecompensationpin.Thisfeatureallowsthecontrolofverylowload,bystillmaintainingagoodeffi-ciency,orofferingverylowinputpowerforzeroloadoperation.Fromthispointofview,thetrans-formerdesignisveryimportant,butthepresentnoteshowsthegoodbehaviorofstandardtrans-formers.2.Inthecasethatthetransformerdoesn’tdemonstrateagoodbehaviorinshortcircuitorshowsanearlyinterventionofprimaryregulation,asimplecircuit(onegeneralpurposePNPbipolartransistor,onesmallcapacitorandoneresistor)greatlyimprovestheperformancesofthewholepowersupply.12/15AN1231-APPLICATIONNOTEANNEX1ComponentListReferenceValuePartNumberNoteCON12PinsconnectorC1220n/275VacC101000u/16VFASeriesPanasonicC11470u/25VFASeriesPanasonicC12470u/25VHFZSeriesPanasonicC2150n/275VacC347u/400VB43503SeriesSiemensC447uC58n2C633n/630VC70u47C84n7/3KVMurataC910nD1BridgeDF06720MD21N4148D3600V-1ATurboSTTA106STMicroelectronicsD43V3-1/2WD5Adj.Shuntreg.TL431STMicroelectronicsD645V-10ASchttkySTPS1045STMicroelectronicsF12.0AT-250VacIC1VIPer50STMicroelectronicsISO1OptocouplerTCDT1101GTemicL22u2ELC08D2R7EPanasonicP12K2R15K1R23K9R356K-1WR46.8R5330R61KR74K7R83K3TR12X56mH42H270500RADIOHMTR215WTransformer2362.5003AELDOR13/15AN1231-APPLICATIONNOTEAnnex2MechanicaldrawingsTransformerspecificationPrimaryinductance:0.82mHPrimaryleakageinductance:30µH(max)CORE:E20-10-6Material:N27Gap:0.4mmTransformerdiagram2362.5003A5ELDOR717Turns0.28mm/G28Turns40.50mm/TIW621083Turns0.28mm/G28Turns0.50mm/TIW91Windings91067452Tape1CoreCenterleg14/15AN1231-APPLICATIONNOTEInformationfurnishedisbelievedtobeaccurateandreliable.However,STMicroelectronicsassumesnoresponsibilityfortheconsequencesofuseofsuchinformationnorforanyinfringementofpatentsorotherrightsofthirdpartieswhichmayresultsfromitsuse.NolicenseisgrantedbyimplicationorotherwiseunderanypatentorpatentrightsofSTMicroelectronics.Specificationsmentionedinthispublicationaresubjecttochangewithoutnotice.Thispublicationsupersedesandreplacesallinformationpreviouslysupplied.STMicroelectronicsproductsarenotauthorizedforuseascriticalcomponentsinlifesupportdevicesorsystemswithoutexpresswrittenapprovalofSTMicroelectronics.TheSTlogoisatrademarkofSTMicroelectronics2000STMicroelectronics-PrintedinITALY-AllRightsReserved.STMicroelectronicsGROUPOFCOMPANIESAustralia-Brazil-China-Finland-France-Germany-HongKong-India-Italy-Japan-Malaysia-Malta-Morocco-Singapore-Spain-Sweden-Switzerland-UnitedKingdom-U.S.A.http://www.st.com15/15