PURPOSE: To constitute the ground protection circuit by using parts at a certain degree sufficiently resistant against normal usage by dropping the output voltage of a voltage creation part and decreasing an output load current when the output load current gets over.
CONSTITUTION: When the output load current gets over by generating ground in a telephone line, the change is transmitted to a control circuit 4. As the result, since the control circuit 4 outputs a control signal to drop the output voltage of a voltage creation part 3, the output voltage of the voltage creation part 3 is dropped so as to decrease the excess output load current caused by the grounding fault. Thus, by using parts at a degree enough resistant against normal usage without especially considering the use of parts with high pressure resistance or high power resistance, when the grounding accident occurs, the over current with the accident can be immediately suppressed and a subscriber circuit 1 can be stably operated.
KINOSHITA KAZUMI
KOSAKO TAICHI
