SWITCHING POWER SUPPLY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a switching power supply device that can reduce the output current when short-circuited without adding a short-circuit protective circuit. SOLUTION: The switching power supply comprises a semiconductor device 30 having a clamp voltage variable circuit 13 that varies an overcurrent protection value generated by a clamp circuit 12 and an oscillation frequency 9B generated by an oscillating circuit 9 in response to a current flowing to a terminal CL from an auxiliary power supply that generates a voltage VCC proportional to the output voltage Vo via a resistor 35. When the output voltage Vo decreases when short-circuited or the like, the voltage VCC of the auxiliary power supply decreases, too, thus resulting in decrease in the overcurrent protection value and the oscillation frequency 9B. COPYRIGHT: (C)2004,JPO