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請問這個開關電源的uc3845的4腳上連接的光耦是起什么作用的呢？
反饋
R/CT The oscilator frequency and maximum Output duty cycle are programmed by connecting resistor Rr to Veand capacitor C+ to qround.
UC3845第4角是RT,CT腳。通常由外置的RC決定振蕩頻率，此處接光耦應該是由外部脈沖信號同步控制3845振蕩頻率。
