| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device capable of stably operating even when instantaneous interruption or the like occurs and also suppressing damage due to an inrush current.SOLUTION: A switching power supply device includes: a switching power supply section PS having a transistor Q1 which is connected to a coil TL1 at a primary side of a transformer T and switches current flowing through the coil TL1, a capacitor C2 which is a smoothing capacitor connected to the coil TL1 and the transistor Q1 in parallel, a triac TAC which is turned on based upon switching of the transistor Q1, and a resistor R2 connected to the triac TAC in parallel; and a switching control section SC which detects a voltage applied to the switching power supply section PS and outputs a signal to stop switching of the transistor Q1 after a predetermined time t1 shorter than a discharge time of the capacitor C2 from when no voltage is detected.SELECTED DRAWING: Figure 1 |
