| 摘要 |
PROBLEM TO BE SOLVED: To surely carrying out the protection of a switching element against an overcurrent and high heat, to prevent internal destruction and to improve reliability as a switching device. SOLUTION: When an overcurrent state to a load 102 is detected and the repetitive ON/OFF control of an FET QA with a built-in temperature sensor is performed, an overcurrent state control circuit 200 times 1 msec in a 1 msec timer circuit 202, then stops overcurrent detection by tuning ON a switching transistor Tr1 by the output of a latch circuit 203 and holds the ON state of the FET QA with the built-in temperature sensor. After timing 9 msec in a 9 msec timer circuit 204 from the overcurrent detection stoppage, that is before 10 msec without the danger of generating the internal destruction of the FET QA with the built-in temperature sensor, the switching transistor Tr3 is turned ON by the output of the latch circuit 207, the switch input of a driving circuit 111 is turned to an L level and the FET QA with the built-in temperature sensor is controlled to an OFF state.
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