Patent ID: 8854018

Claim:
A control circuit for reducing touch current of a power converter, wherein the power converter is a power converter with power factor correction (PFC), the control circuit comprising: an auxiliary pin for receiving a voltage corresponding to an auxiliary winding of the power converter; a zero-crossing signal generator for generating a zero-crossing signal according to the voltage and a first reference voltage; a feedback pin for receiving a feedback voltage corresponding to an output voltage of the power converter; a frequency limiting signal generator for generating a frequency limiting signal according to the feedback voltage and a second reference voltage, wherein the frequency limiting signal generator comprises: a compensation voltage generation unit for generating a compensation voltage according to the feedback voltage and a third reference voltage; and a first signal generation unit for generating the frequency limiting signal when the compensation voltage is less than the second reference voltage; a gate signal generator for generating a gate control signal to a power switch of the power converter according to the zero-crossing signal and the frequency limiting signal; and a burst mode signal generation module, comprising: a first comparator for generating a comparison signal according to the compensation voltage and a burst mode reference voltage, wherein the burst mode reference voltage is less than the second reference voltage; and a second signal generation unit for generating a burst mode signal to the gate signal generator according to the comparison signal; wherein the gate signal generator is further used for generating the gate control signal to the power switch according to the burst mode signal and the zero-crossing signal, and a frequency of the gate control signal is varied with the compensation voltage between the burst mode reference voltage and the second reference voltage.