| 摘要 |
<P>PROBLEM TO BE SOLVED: To implement a high power efficiency switching power supply. <P>SOLUTION: A switching power circuit includes: first and second switching elements connected in series with a DC power supply; a resonance circuit; a transformer having a primary side winding and first and second secondary side windings; an output terminal for supplying a rectified/smoothed voltage of the first secondary side winding to an external load; pulse generation means for generating pulses for opening and closing the first and second switching elements alternately to cause a resonance current to flow through the primary side winding and the resonance circuit; detection means for detecting whether or not a power consumption level at the external load connected to the output terminal is at least a predetermined power level; and switching means for inputting a predetermined voltage into the pulse generation means when the detection finds the predetermined power level reached or exceeded, and inputting a voltage that is a rectified/smoothed voltage of the second secondary side winding into the pulse generation means when the detection finds the predetermined power level unreached. <P>COPYRIGHT: (C)2013,JPO&INPIT |
