| 摘要 |
In a switching power supply of the present invention, when a voltage output from start-up means is greater than a driving voltage produced by output means, the voltage from the start-up means is provided to control means, whereby the switching power supply can be started up reliably. Furthermore, when the voltage output from the start-up means is less than the driving voltage produced by the output means, the current path is blocked in the start-up means so that no voltage is provided to the control means from the start-up means, whereby it is possible to reduce the power consumption during the steady operation.
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