| 摘要 |
PROBLEM TO BE SOLVED: To prevent the malfunction of a switching power supply when an operating state rapidly shifts from a low power consumption state, in which the operation of a power factor improvement control circuit is stopped, to a normal power state. SOLUTION: This switching power supply is provided with an auxiliary control circuit 20 for controlling an overload protection cancelling circuit 10 so as to cancel the operation of an overload protection circuit 70 for only prescribed period of time after a load circuit 57 is shifted from the low power consumption state to the normal power state and the power factor improvement control circuit 6 starts to operate, so that even when the operating state shifts from the low power consumption state, in which the operation of the power factor improvement control circuit 6 is stopped, to a normal load state, the operation of the overload protection circuit 70 is cancelled until the prescribed period of time passed after the power factor improvement control circuit 6 starts to operate. Thus, even in such a state, such malfunction is prevented that the overload protection circuit 70 operates and interrupts an output signal from an output terminal 61 of a main control section 60, and consequently, a main switching element 52 is switched off. COPYRIGHT: (C)2005,JPO&NCIPI
|
