09201034：
另外一個方法你教我去調把R20來減小…..讓它先不采樣用電位器來…..調節R25看一下改變11腳的采樣電壓來控制前面的PWM輸出占空比….PWM會改變….但是我的開路電壓最大還是只能到200V….如果不加后面紅色框起來的部分…可以到400V….可是紅色框框是為了做電壓SENSE用的(上面我有貼電路圖)….不加應該不可以吧….它的DATASHWWT有說到一段話….FLTC:ThevoltageonVOUTSENSEisproportionaltolampvoltage.Ifthatvoltageistoohighortoolow,thelampiseitheropen,shorted,ornotyetrunning.Duringnormaloperation,thereisacapacitorconnectedtoFLTC,andthiscapacitorisdischargedto0VbyacurrentsourceinsidetheUCC3305.TheUCC3305monitorsthevoltageonVOUTSENSEandcomparesittoaninternal83mVlowerthresholdanda2Vupperthreshold.Ifthevoltageisoutsidethiswindow,thentheICwillpulluponFLTCwithacurrentofapproximately250nA.IfthefaultremainslongenoughtochargetheexternalFLTCcapacitorover5V,thecontrollerdeclaresacatastrophicfaultandshutstheICdown.TheICwillstayshutdownuntilpowerisremovedfromBOOST.IfthefaultclearsbeforetheFLTCcapacitorreaches5V,thecapacitordischargesdownto0V.Thisdischargecurrentisapproximately50nA,representingafivetimeslongerdischargeratethanchargerate.是不是超過2*120V或低于83mV*120它的IC就會SHUNTDOWN…我還把它的匝數比調到10:85還是電壓沒增加多少…那我要如何辦到300V以上….還是我的觀念錯了…可以幫我解答一下嗎….我研究好久都沒有什麼發現…而且還燒掉1顆IC了…我只有8顆可以用…你可以在幫幫我嗎….