| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an abnormal voltage protection circuit capable of preventing damage to electronic components in an electronic device when an improper AC adaptor is attached to the electronic device. <P>SOLUTION: The abnormal voltage protection circuit of an electronic device fed with power from an external DC power supply unit includes a power feed detecting circuit 1 for detecting power feed, an overvoltage detecting circuit 2 for detecting overvoltage, a control circuit 3 operating based on the input of the output of the power feed detecting circuit 1 and the output of the overvoltage detecting circuit 2, and a gate circuit 5 connected between the external DC power supply unit and the electronic device, and operating based on the output of a microcomputer 3. The microcomputer 3 brings the gate circuit 5 into a conduction state after a predetermined time elapses after the power feed detecting circuit 1 detects the power feed, and brings the gate circuit 5 into a non-conduction state immediately after the overvoltage detecting circuit 2 detects the overvoltage. <P>COPYRIGHT: (C)2010,JPO&INPIT |
