| 摘要 |
The switching power supply can reduce electric power consumption in the standby mode, while preventing overcurrent at the start of the switching power supply, as well as providing protection against short-circuiting. The switching power supply includes a switching control circuit that provides a PFM control when a light-load judging section thereof judges based on a feedback signal that the load is light, a PWM control when light-load judging section thereof judges based on the feedback signal that the load is not light, setting the minimum ON-period of a switching device when the predetermined condition is met during the PWM control such that the minimum ON-period during the PWM control is shorter than the ON-period of the switching device during the PFM control, and turning off the switching device when the current flowing through the switching device exceeds the allowable value to the higher side after the elapse of the minimum ON-period.
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