| CPC H02M 3/33523 (2013.01) [H02M 1/0058 (2021.05); H02M 1/0006 (2021.05)] | 20 Claims |

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17. A method applied in a circuit for Flyback switching power supply, the circuit comprising a transformer having a primary winding and an auxiliary winding, wherein the method comprises:
generating a control signal based on a voltage at a common node of a first capacitor and the auxiliary winding, wherein the circuit further comprises a first switch, a first terminal of the first switch is connected to a non-dotted terminal of the auxiliary winding through the first capacitor, a second terminal of the first switch and a dotted terminal of the auxiliary winding are connected, respectively, to a ground, and the common node of the first capacitor and the auxiliary winding is configured to connect to a non-dotted terminal of the primary winding;
controlling, based on the control signal, to turn on the first switch of the circuit to perform zero voltage switch of a power switch of the circuit.
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