| 摘要 |
In relation to a starting circuit for supplying a DC supply voltage to the gate of a main switching device at a power-on to start a switching operation, a holding circuit for holding a starting voltage obtained in the starting circuit is provided. The potential at the gate of the main switching device is increased immediately from a turn-off to turn on the main switching device repeatedly, realizing a smooth transition to the steady oscillation state. This allows the switching power supply to readily start even under the condition of a low supply voltage and a heavy load. This makes it possible to improve the starting characteristic and to allow for lower power consumption.
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