公开(公告)号：US06816348B2

公开(公告)日：2004-11-09

申请号：US09683651

申请日：2002-01-29

申请人： Chung-Ho Chen ,  Chien-Hao Huang ,  Gin-Yuan Sheh

发明人： Chung-Ho Chen ,  Chien-Hao Huang ,  Gin-Yuan Sheh

IPC分类号： H02H320

CPC分类号： H02H11/002 ,  H02H3/20 ,  H02H11/006 ,  Y10T307/839

摘要： An input protection circuit is provided for protecting internal circuitry of a handheld electric device. The internal circuitry has a positive input node and a ground node. The input protection circuit includes a power socket having a positive input node and a ground node, a bipolar junction transistor (BJT), a metal-oxide semiconductor (MOS) transistor for controlling the on and off states of the BJT, and an overvoltage protective circuit. An emitter of the BJT is electrically connected to the positive input node of the power socket, and a collector is electrically connected to the positive input node of the internal circuitry. When a reverse DC voltage or a DC voltage exceeding a threshold inputs from the power socket, the overvoltage protective circuit will turn off the MOS transistor, thereby turning off the BJT to prevent damages of the internal circuitry.