摘要 |
The present invention provides a power supply circuit performing constant voltage control by switching frequency control and achieving minimization of a necessary control range of the switching frequency control and implementation of a configuration ready for a wide range. A switching power supply circuit includes switching means, switching driving means, the insulating converter transformer, a primary side series resonance circuit, a secondary side series resonance circuit, secondary side DC output voltage production means, constant voltage control means, and composite coupling coefficient setting means. |