| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a small and long-lasting switching power supply circuit capable of reducing periodical ripples and reducing occurrence of harmonic current. <P>SOLUTION: The switching power supply circuit comprises: a rectifier circuit 11 that converts alternating current into pulsating current; a first semiconductor switching element SW1 and a smoothing capacitor C that are serially connected to each other between the output lines of the rectifier circuit 11; and a diode D that is connected between a current supply point P on the line and an intermediate connection point S of the first semiconductor switching element SW1 and the smoothing capacitor C, and supplies charge to the smoothing capacitor C from the current supply point P. The first semiconductor switching element SW1 is turned on when a voltage V1 of the pulsating current is lower than the threshold voltage. While the pulsating voltage V1 is low, the charge accumulated in the smoothing capacitor C is supplied to a load, thereby suppressing the variation in the voltage and current of the load. <P>COPYRIGHT: (C)2012,JPO&INPIT |
