Patent ID: 8179700

Claim:
A control circuit of a power converter, comprising: a switch coupled to a transformer for switching the transformer; a sampling circuit coupled to the transformer for sampling a reflected voltage of the transformer to generate a voltage signal in accordance with the reflected voltage; a switching circuit coupled to the sampling circuit for generating a switching signal to control the switch and to regulate the output of the power converter in response to the voltage signal; a conversion circuit generating an adaptive signal correlated to an input voltage of the power converter and transmitting the adaptive signal to the switching circuit; wherein the adaptive signal is coupled to adjust a minimum on time of the switching signal, and the minimum on time of the switching signal is inverse proportion to the input voltage of the power converter; wherein the sampling circuit comprises: a sample unit coupled to the transformer to generate the voltage signal by sampling the reflected voltage of the transformer; and a sample-signal generation circuit generating at least one sample signal in response to the switching signal; wherein the sample signal is coupled to control the sampling time of the sample unit.