Patent ID: 7911815

Claim:
A primary-side feedback control device for a power converter, the primary-side feedback control device comprising: a control unit for generating a pulse signal according to a feedback signal for controlling on and off states of a switching transistor of the power converter; a comparator coupled to an auxiliary winding of a primary side of the power converter for generating at least one control signal according to a voltage on the auxiliary winding and a reference voltage; a sample-and-hold unit coupled to the auxiliary winding, the comparator and the control unit, for generating the feedback signal according to the voltage on the auxiliary winding and the at least one control signal; and a voltage generator coupled to the control unit, the comparator, and the sample-and-hold unit for generating the reference voltage outputted to the comparator according to the feedback signal wherein the sample-and-hold unit comprises at least one switch and one capacitor.