Patent ID: 7898823

Claim:
A switching converter, comprising: a transformer, comprising a primary winding and a secondary winding, for transforming an input voltage into an output voltage; a switching transistor, a first end of which is directly connected to the primary winding of the transformer and a control end of which is for receiving a control signal, for controlling operation of the transformer according to the control signal; a coupling circuit, having a first terminal directly connected to the first end of the switching circuit, for generating a coupled signal at a second terminal of the coupling circuit according to a voltage signal at the first end of the switching transistor; and a regulating circuit, directly connected to the second terminal of the coupling circuit, for receiving the coupled signal and accordingly generating a detecting result, and generating the control signal according to the detecting result; wherein the voltage signal at the first end of the switching transistor is different from the coupled signal at the second terminal of the coupling circuit; wherein the regulating circuit comprises: a zero-cross detecting circuit, coupled to the coupling circuit, for detecting a zero-crossing point of the coupled signal and generating the detecting result; and a pulse width modulation (PWM) signal generator, coupled to the switching transistor, for generating the control signal to control the switching transistor according to the detecting result.