| 摘要 |
PROBLEM TO BE SOLVED: To enhance the efficiency by blocking conduction of a switching element when the output voltage therefrom is high thereby suppressing generation of a spike current and power loss. SOLUTION: A switching power supply comprising a transformer having a primary winding and at least one secondary winding, a circuit for smoothing the secondary winding voltage of the transformer, a control circuit outputting an on/off circuit depending on the output voltage from the smoothing circuit, a switching element for supplying power to the transformer in response to an on/off signal of the control circuit, and a snubber circuit absorbing the surge voltage of the switching element is further provided with an on-delay circuit for not turning the switching element on until the output voltage Vsw1 thereof is lowered when it is higher than a DC power supply voltage Vin.
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