| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that when an oscillation stop signal is input to a feedback terminal of a power supply control IC, the oscillation stop signal is latched, this latch state is kept until power supply from the external is interrupted, but much charge is still charged in a first electrolytic capacitor at the time point when the voltage of a second electrolytic capacitor for latch is lowered and the latch state is released because the capacity of the first electrolytic capacitor is remarkably larger than the capacity of the second electrolytic capacitor, so that power occurs in a secondary-side circuit in spite of a short time when the power supply control IC is resumed and ON/OFF of a switching element is resumed.SOLUTION: A power supply device is provided with a discharge circuit for monitoring the voltage of a second smoothing capacitor and discharging charges remaining in a first electrolytic capacitor when the voltage of the second smoothing capacitor decreases to a predetermined voltage at which the latch state can be kept.SELECTED DRAWING: Figure 2 |
