| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply of a self-oscillating resonance- type switching power supply which can conduct an intermittent oscillation operation in a light-load state with a small number of components and can improve the efficiency in the light-load state. SOLUTION: A first switching control circuit has a first ON-time control circuit, which controls an ON-time of a first switching device Q1 so as to make a first control transistor electrically continuous before the first switching device Q1 is turned on by a voltage induced in a first drive winding, in order to prevent the first switching device Q1 from being turned onto stop an oscillation operation in a light-load state. A second switching control circuit has a second ON-time control circuit, which controls an ON-time of a second switching device Q2 so as to make the energy discharge from a secondary winding finished, before the ON-time of the second switching device Q2 is finished in the light- load state. COPYRIGHT: (C)2003,JPO
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