| 摘要 |
PROBLEM TO BE SOLVED: To improve the starting performance in a low-loss and low-noise switching power supply device consisting of a voltage feedback, self-excitation complex resonance type series converter for driving a switching element with a voltage induced in an auxiliary winding, and capable of achieving significant circuit simplification and cost reduction. SOLUTION: When a power MOSFET Q1 is turned ON by giving a starting pulse to a gate of one power MOSFET Q2 by relaxation oscillation of a starting circuit IGN, and then by giving a feedback voltage in a feedback winding L13 corresponding to the other power MOSFET Q1 to the power MOSFET Q1 by switching thereof, an amplifier 12 is provided on the feedback winding L13, and a limiter 11 is provided so that the induced voltage does not exceed an allowable value of the power MOSFET Q2 when moved to a stationary oscillation. Accordingly, the power MOSFET Q1 is reliably turned ON and started even if only a small pulse is induced by the effect of a smoothing capacitor C3 under discharge. COPYRIGHT: (C)2010,JPO&INPIT
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