| 摘要 |
PROBLEM TO BE SOLVED: To avoid welding of the relay contact in a power supply having an overvoltage protection circuit employing a relay. SOLUTION: The power supply 1 comprises a power circuit 10, a control IC 30, and a relay 111 provided between a battery 102 and the power circuit 10. The power circuit 10 comprises transistors M1 and M2 and generates a voltage required by a load 200 according to a control signal generated by the control IC 30. The control IC 30 normally controls the output of the power circuit 10 depending on the voltage required by the load 200. When an input voltage Vin exceeds a threshold, the current is reduced by turning the transistors M1 and M2 off and then the relay is turned off. When the input voltage Vin increases furthermore, the transistors M1 and M2 are controlled such that the input voltage Vin coincides with a predetermined clamp voltage. COPYRIGHT: (C)2007,JPO&INPIT
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