| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an overvoltage protection circuit that effectively limits an overvoltage with a correct voltage and allows an internal circuit to operate continuously. <P>SOLUTION: A protection circuit unit 13 in which a switching element (an FET 13a) and a Zener diode (a Zener diode 13b) are connected in series is interposed between a power-supply line 15 and a ground 16. When a voltage detection circuit unit 11 detects that a voltage between the power-supply line 15 and the ground 16 increases over a predetermined potential, a control circuit unit 12 causes the switching element to conduct and limits an overvoltage by a short-circuit path formed among the power-supply line, the protection circuit unit 13, and the ground. At this time, the Zener diode operates as a variable resistor while following a reverse current. <P>COPYRIGHT: (C)2013,JPO&INPIT |
