Patent ID: 9537417
Date: 2017-01-03
CPC Classifications: G01R,H02M

Claim:
1. A power supply control circuit connected to an alternating current power source via an input circuit having a capacitor, comprising: a discharging circuit which discharges accumulated electric charge remaining in the capacitor when the alternating current power source is cut off; a peak hold circuit which detects a voltage signal increasing and decreasing in accordance with an increase and decrease in a terminal voltage of the capacitor, and, during each cycle of a plurality of cycles of the alternating current power source, holds a peak voltage representing a peak voltage of the alternating current power source and discharges the held peak voltage in response to a reset signal; a level comparison component which generates the reset signal by comparing the voltage signal with a reference voltage signal level supplied to the level comparison component based on the peak voltage representing the peak voltage of the alternating current power source held by the peak hold circuit; and a timer circuit, connected to the level comparison component, whose timing operation is reset by the reset signal, the timer circuit configured to cause the discharging circuit to discharge the accumulated electric charge when the timer circuit detects that the timing operation has elapsed a predetermined time measurement period without being reset.