Patent ID: 8780587

Claim:
A switching regulator, comprising: a rectifier circuit, for converting an AC power to a rectified power, wherein the rectified power includes an input voltage and an input current; a transformer, which includes a primary winding and a secondary winding, wherein the primary winding is for receiving the rectified power, and the secondary winding is for generating an output voltage; a power switch, which is coupled to the primary winding, for switching according to an operation signal to convert the rectified power to the output voltage; and a control circuit, which is coupled to the power switch, for generating the operation signal according to the rectified power to control the rectified power within a predetermined range, the control circuit including: a power index generation circuit, for generating a power index according to the input voltage and the input current; an amplifier circuit, for generating an error signal according to the power index and a first reference signal; a control signal generation circuit, for generating a control signal according to the error signal; a driver circuit, for generating the operation signal according to the control signal; a low-pass-filter (LPF) circuit, which is coupled to or integrated in the power index generation circuit or the amplifier circuit, for filtering a high frequency band; an output voltage detection circuit, for generating an output voltage detection signal related to the output voltage; and a compensation circuit, for generating the first reference signal which is inputted to the amplifier circuit according to the output voltage detection signal and a second reference signal.