| 摘要 |
PROBLEM TO BE SOLVED: To surely discharge a reset capacitor without shutting off power for every instantaneous interruption. SOLUTION: The invention relates to a voltage detection circuit 53 for detecting drop of an input voltage to a switching control circuit 5 and operating a discharging circuit 55 for discharging a reset capacitor C2 provided in the switching control circuit 5, wherein a signal for comparison is produced from the input voltage in such a way that its voltage reaches a recovery determination value Vr after the lapse of a predetermined time Ta from the time of recovery after the detection of the input voltage drop, and the reset capacitor C2 is discharged by operating the discharging circuit 55 continuously from the detection of the input voltage drop until the voltage of the signal for comparison exceeds the recovery determination value Vr. COPYRIGHT: (C)2011,JPO&INPIT |
