| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply capable of lowering switching frequency as a load becomes light, and capable of reducing switching loss. SOLUTION: By making a ringing generating circuit 20 generate the same ringing with the ringing that occurs in a transformer 11 during the off-period of a switching element 6, the ringing is detected by a comparator circuit 31. From this detected ringing, the number of times of ringing is counted by a bottom counter circuit 33 to generate a count pulse signal. Based on this generated count pulse signal, a delay signal is generated by a delay circuit 34. In accordance with this delay signal, the on-period of the switching element 6 is delayed. COPYRIGHT: (C)2003,JPO
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