武士：
500uH差不多,好象是你的咂比有問題,19:1在400V時次級就有21V已經(jīng)超過了NCP1650的VCC上限了.所以你在低壓是能啟動而高壓不行(NCP1650過壓保護了)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.我試著算了一下,你看看和你的結(jié)果一樣嗎?注意電感的峰值電流>4A