武士：
500uH差不多,好象是你的咂比有问题,19:1在400V时次级就有21V已经超过了NCP1650的VCC上限了.所以你在低压是能启动而高压不行(NCP1650过压保护了)NCP1650DesignPartsListNCP1650DesignAidProvidedbyONSemiconductorForasystemwiththefollowingspecifications:Pomax=250wattsVinmax=265VrmsVinmin=85VrmsfLINE=50HzfSwitch=100kHzVout=400voltsh=0.9L=500uHThefollowingpartsarerequired2:Cout1=100uFacscale=0.010dividerratioC2 =0.1uFRShunt=0.03ohmsC3 =10nFR3=1,500ohmsC4 =1nFR7=600ohmsC7 =47uFR8=10,000ohmsC8 =22uFR9=68,000ohmsC9 =3.3uFR10=10,000ohmsC11=1.0nFR13=100kOhmsCT=470pFNotes:1.Ripplecurrentcalculationsforinputandoutputcapacitorsareplottedonsheet3a.2.Thesecomponentvaluesarearecommendedstartingpoint,however,ONSemiconductordoesnotguaranteethatthecircuitwillmeetallspecifications.Normaltroubleshootingandadjustmentsmaybenecessary.3.AdditionalcomponentswillbeneededifimplementationofanEMIfilterisnecessary.我试着算了一下,你看看和你的结果一样吗?注意电感的峰值电流>4A