PURPOSE: A power supply device is provided to prevent malfunction due to the noise by implementing a protective action. CONSTITUTION: A converting part(110) converts an applied voltage into a predetermined level. A switching part(120) switches to control the current flowing into the converting part. A sensing part(130) senses the generation of excessive current. The excessive current is sensed over a predetermined number. A control part(140) performs a protective action. [Reference numerals] (110) Converting part; (142) Counter; (144) Delay; (146) Protector; (148) Control signal generator;
