| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small, lightweight, low noise and high efficiency switching power supply of simple circuitry. SOLUTION: The switching power supply comprises a rectifying/smoothing circuit connected between the output terminals of a rectifier circuit B1 and including a series connection of a diode DP and a smoothing capacitor C1, a circuit connected between the terminals of the smoothing capacitor C1 and including a series connection of a primary winding P and a switching element Q1, a circuit connected between the output terminals of the rectifier circuit B1 and including a series connection of a resonance circuit consisting of a reactor LP and a capacitor CP and a switching element Q2, a diode D3 connected between the joint of a primary winding P and the switching element Q1 and the joint of the resonance circuit and the switching element Q2, a first control circuit 12 performing on/off control of the Q1 such that the output voltage obtained by rectifying a voltage induced in the secondary winding S has a predetermined voltage, and a second control circuit 14 for turning the Q2 on simultaneously with the Q1 and turning the Q2 off after an on period shorter than that of the Q1. COPYRIGHT: (C)2008,JPO&INPIT
|
