白炽灯泡：
补充:应用文档中对启动电路的描述、、2.2Start-upcircuitAsalreadymentionedintheintroductionsection,thecontrollerislocatedonthesecondarysideofthepowertransformer,andforthisreason,astart-upcircuithastobeprovidedforacorrectsystemactivation.Thestart-upcircuitisbasedonadiacsendingatrainofcontrolledpulsestothelowsidedrivesection;thefloatingdrivesectionisenergisedbythesecondsecondarygatedrivetransformerwinding.AssoonastheL5991awakes-up,itgeneratesapwmsignalenablingthestart-upcircuit.大概翻译为:前面已经介绍控制器放在二次侧,因此启动电路就必须提供合适的方法令IC工作,本设计基于采用二端交流开关送出一触发脉冲给低边驱动部分,高变MOS再由二次侧供电,L5991即刻唤醒,即产生PWM信号从而完成启动.此说明中的二端交流开关是怎么一回事?这个启动的描述,我没弄懂、、谁知道的帮忙结合原理图解释一下啊