| 摘要 |
A switching power supply circuit includes a direct current (DC) power supply input; a voltage divider connected between the DC power supply input and ground; a transformer including a primary winding, a secondary winding, and an assistant winding; a pulse generating circuit including a first transistor, a second transistor, an oscillation capacitor, and an oscillation resistor; an output; and a feedback circuit adjusting a duty ratio of a pulse signal in the assistant winding. The DC power supply input is grounded via the primary winding, two conducting electrodes of the second transistor. A control electrode of the second transistor is connected to an output of the voltage divider. An output of the voltage divider is connected to a control electrode of the second transistor and is grounded via two conducting electrodes. A control electrode of the first transistor is grounded via the assistant winding and grounded via the oscillation capacitor and the oscillation resistor connected in series.
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