To realize an overcurrent protection circuit for a load circuit to which power is supplied by a power circuit of a low power consumption, by utilizing repeating of the intermittent output of a DC power part or the intermittent energization of the transformer and charging/discharging of a filter capacitor.
This overcurrent protection circuit 1 for a load circuit 3 to which power is supplied by a power circuit 2 including a DC power supply part 21; a capacitor 22 charged by a DC voltage outputted from the DC power supply part 21; a feedback part 23 for controlling the DC power supply part 21 so that DC voltage is not outputted, when a load current value passing through a common contact between the capacitor 22 and a load current 3 is larger than a prescribed value, and so that DC voltage is outputted, when the load current value is smaller, is provided with a determination means 11 for determining whether the pulse cycle of load voltage is shorter than a prescribed cycle and a shutdown means 12 for forcibly shutting down the output of the DC power part 21, considering it as being abnormal, if the pulse cycle is shorter than the prescribed cycle.
Jun Tsuruta
Shigeru Tsuchiya
Masaya Nishiyama
Higuchi Souji