| 摘要 |
PROBLEM TO BE SOLVED: To reduce switching loss of a switching power supply apparatus and to stabilize the operation of the switching power supply. SOLUTION: This switching power supply apparatus stores energy in a transformer 21 by turning on an N-MOS 22 and discharges the energy from the transformer 21 by turning off the N-MOS 22. When discharging of the energy is finished, a ringing voltage is applied to the N-MOS 22. A timer 38 detects lapse of a prescribed time, after the N-MOS 22 is turned on previous time. A counter 37 detects that the number of ripples has reached a prescribed value. If one of the counter 37 and the timer 38 outputs the detection result first, an AND circuit 36 and an OR circuit 39 set a timing, when the N-MOS 22 is turned on again. As a result of such a constitution, the N-MOS 22 can be turned on before the ringing voltage attenuates. COPYRIGHT: (C)2003,JPO
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