| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply which has realized control of generation of surge current and surge voltage, improvement of efficiency and reduction of noise by lowering switching loss due to zero-volt switching under the light load condition. SOLUTION: In an insulation type DC-DC converter for full-wave rectification in the secondary side of a transformer, a delay circuit 8 delays, as much as the predetermined delay time, the switching signals G1 and G3 outputted from a switching control circuit 7 for a couple of switch means 11 and 13 which are alternately turns ON and OFF for inverting a current 13 flowing into the primary coil 3a of the transformer 3 when a load current detecting means 9 has detected that a load current is smaller than the predetermined threshold. Such a delay time is set substantially equal to the (1/4) period of resonance as a result of contribution of a self-inductance of the primary coil 3a of the transformer.
|
