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線圈自感的內阻當然有影響,但是最大的問題在於你是用2腳來檢測輔助輸出的電壓,從而控制輸出的電壓.當你增加輸出電流時,因為漏感使輔助輸出的電壓不跟主輸出的電壓下降,反而增加,所以會使主輸出的電壓不隱.

HowtochooseE-cap?1.Outputvoltageshouldbebelow80%ofE-capvoltage.2.RipplecurrentthroughtheE-capshouldbewithintheE-capspecification.  Currentripplecanbemeasuredorcalculatedfromthecircuit.3.ESR*ripplecurrent=Ripplevoltage.4.twogradeoftemperature,85Cor105C.  Choosebasedoncost,sizeandtemperatureontehe-cap.5.Lifetime,at100%ripplecurrent,canmeasurethecasetemperatureonthee-capandthenuseformulafromE-capcompanytocalcultatethelifetimeoftheE-cap.  Lifetimeshouldbe>waranteetimeofthepowersupply.Hopethiscouldhelp

輔助輸出繞組及主輸出繞組間的漏惑會使隱壓變差.繞組次序:初級;次級;輔助輸出繞組．2．輔助輸出繞組Diode後,電容前加電阻作濾波．

34823腳上的電壓不是不能超過1V,而是當3腳上的電壓達到1~1.1V時,芯片就會把MOS管關掉．3腳對地的等效阻值是決定流過MOS管電流的最大嶧值.

thereisalotofDC/DCmoduleavailableinthemarkettoconvert12Vto5V.  JustsearchthewedforDC/DCmodule.Ifyoudon'tcareaboutthepowerlossandheatdissipation,youcanuseaLDOIC.

InmyexperinceinshortcircuitofLLC,itisreallyaheadache.  Finally,weusedtwomodesofcurrentprotection.  ThereisadelayedOCPandalsoaConstantcurrentmode.  Thedelaytimecanbesetfrom1sto6s,defaultis3s,duringthis3sdelay,theconstantcurrentmodewilltakeplace,limitingtheoutputcurrent,iftheoverloadcurrentisnotremovedafter3s,theunitwillentedhiccupmode.  TrytoaddadelaytoyourOCPcircuit.

1.PeakcurrentlimitIdlim,thiswillswitchofftheMOsfetwhenId+Ifbreachthislevel,duringshortcircuit,Vfbwillbezero,therefore,themaximumcurrentthroughthetransformerwindingwillbeIdlim.  Youcanthenestimatethepowerintothepowersupplyduringshortcircuit,byknowingtheIdlim,Lp.2.OVPprotectionbyVddovp,thevoltageis42V.  Duringshortcircuit,thereflectedvoltageontheVddmayreduce,dependsondifferenttransformerworkmanship,theperformancewillbedifferent.  ThisfeatureisgoodforOVP,butforshortcircuit,ifyourelyonthisfeature,theperformancemayvaryduringMassProduction.

CantryBelow:1.Frequency=100K2.Np=25T,Ns=3T3.airgap=0.17mmLp=362uHAtVin=65VdcIp=1.5ABac=130mT,Bdc=148mTTotalB=278mT

at90Vacinput,60Hzpeakinputvoltageis127Vdcyourcap=33uFafterchargeofyourinputcap,theenergyfortheoperationwillcomefromcapacitor,therefore,lowestvoltageonthecapacitorisVl1/2*33u*(127^2-Vl^2)=18W*8mSVl=86Vthereforeyourmeasuredripplevoltageon33uFcapis127V-86V=41VIfthevariationofDutycycleonlyhappenintheLowinputvoltageandfullload,mostprobablycausedbytherippleonourinputcapacitor.  Thisisnormal,otherwise,youwillseetherippleontheoutputvoltage.

1.PleasechecktheVddvoltageduringshortcircuit,coulditcomedowntobelow8V?2.theCurrentlimitofthisICisverywide,from0.56Ato0.84A.  Thiswillmakedesignverydifficultforwiderangeinput.  Normally,willdesignthetransformertooperatewithIpof0.56Aatlowestlineinput.  Tocutconner,canassumeoperationatnominalinputvoltageandcurrentlimitis0.7A,thendesigntransformertooperateatthiscondition,thenathighinputvoltage,makesurethattheVddwillfallbelow8Vdurignshortcircuit.