| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device which supports reduction in surge voltage applied to a rectifier diode and transient response performance at the same time, and which has a simple configuration.SOLUTION: A quasi-resonant switching power supply device comprises: a switching element connected to primary winding of an isolation transformer; a resonance capacitor provided in parallel with the switching element; an output capacitor Co connected to secondary winding S of the isolation transformer via a rectifier diode D; and a control circuit for turning on and off the switching element. The switching power supply device further comprises: a restart circuit for outputting a restart signal after a predetermined time Tres has elapsed from turning off of the switching element when the switching element is not turned on, for turning on the switching element; and an initial operation setting circuit for setting a delay time Tres set for the restart circuit to a longer time than in a normal operation after completion of start-up for a certain period of time at the start-up of the device. |
