| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply, capable of protecting other devices from an overcurrent which occurs to the power supply and of unfailingly detecting its overcurrent abnormality, even if power is supplied from a single constant voltage source to a plurality of devices. SOLUTION: If an overcurrent occurs, it is detected by a current-detecting circuit 11, which compares a load current I flowing into a device M with a reference current value I*, and a current-controlling element 12 is actuated according to the output of the current-detecting circuit 11. Because the load current 1 is limited by the reference current I* and an overcurrent which flows into the device M is controlled, no overcurrent causes a voltage drop to occur, thereby affecting no other devices. At this time, a time-counting circuit 13 measures a period of time, when the load current I continuously exceeds the reference current I*. When this continuing time exceeds a standard continuing time which corresponds to the continuing time of a transient overcurrent, which occurred to the power supply, i.e., when the overcurrent caused by a short circuit, etc., flows continuously, the overcurrent is detected as abnormality of the power supply. |
