chenpen：
Advantagesofdiscontionuousoperation:1.Asmalltransformercanbeusedbecausetheaverageenergyislow,useoffewerturnsalsotranslatesintoredusedI^2*Rlosses.2.Stabilityiseasiertoachievebecauseatfrequencieslessthanonehalftheswitchingfrequencythereisnonetinductancereflectedtothetransformersecondary.andhencenosecondpoleintheinputtooutputtransferfunction.3.OutputrectifiesareoperatingatZerocurrentjustpriortobecomingreversebiased.thereforereverserecoveryrequirementarenotcriticalfortheserectfiers.4.similarly,thepowertranssitorturnsontoacurenlevelwhichisinitiallyzero,soitsturnontimeisnotcritical.5.transsitorturnontozerocurrentalsoresultsinlowRFIgeneration.Disadvantange1.Transistoranddiodepeakcurrentrequirementareapporoximatelytwice.2.Transformerleakageinductanceishigh,resultinsomelossofcross-regulation.3.HighvalueofripplecurrentmakeEcapquitestringent.