Power supply device

摘要

A power supply device has a pulse width control circuit (5) for controlling voltage converting operation of a voltage converting circuit (1) by changing a pulse width. A momentary interruption detecting circuit (2) detects a change in an output voltage when the output voltage suffers a momentary interruption over a short period of time. A full short-circuit detecting circuit (3) detects a change in the output voltage when the output voltage suffers a short circuit over a very short period of time. A short-circuit control circuit (4) stops a pulse width changing control process of the pulse width control circuit a predetermined period of time after the momentary interruption detecting circuit (2) has detected that the output voltage suffers a momentary interruption, and stops the pulse width changing control process of the pulse width control circuit immediately when the full short-circuit detecting circuit (3) detects that the output voltage suffers a short circuit.