| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit for reducing a switching loss in a free wheeling FET, and stably and surely operating the free wheeling FET regardless of a load voltage. SOLUTION: The power supply circuit is provided with a switching semiconductor element, its control circuit, first and second rectifying elements connected to a secondary winding in a transformer, a drive circuit, and a smoothing inductor. The second rectifying element comprises a field effect transistor for operating as the free wheeling FET. The drive circuit drives the free wheeling FET, and comprises a secondary winding in the smoothing inductor, a rectifying circuit connected to the secondary winding, and an inductance element and an impedance element connected to an output terminal of the rectifying circuit. A charge in a capacitance between a gate and a source of the free wheeling FET can be discharged by discharging energy accumulated in the inductance element through the rectifying circuit. COPYRIGHT: (C)2007,JPO&INPIT
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