| 摘要 |
PROBLEM TO BE SOLVED: To hold operation reliability of power supply, overcurrent protection, etc., even at low temperatures. SOLUTION: If a thermal FET 11 of a switching circuit having a current vibration type cutting-off function is heated up to break and its ambient temperature is lower than specific temperature, a heating cutoff detecting circuit 102 detects the heating cutoff and output its detection signal to the outside. The detection signal is counted by a microcomputer, etc., and a driver is notified that the count value nearly reached a heating cut-off frequency at low temperatures where a fault-free operation is quaranteed. Then the operation reliability of the switching circuit having the current vibration type cutoff function is maintained, even at low temperatures if the switching circuit having the current vibration type cutoff function is replaced. |
