Control circuit for controlling a power switch and associated control method

A control circuit for controlling a power switch in an SMPS, comprising a peak current control circuit configured to turn off the power switch when a current flowing through the power switch exceeds a threshold, and the peak current control circuit further configured to control a peak value of the current to vary at a first frequency and control an enveloping line of the peak value to vary at a second frequency, wherein the second frequency is lower than the first frequency.

A control method for controlling a power switch in a SMPS, comprising:

• jittering a current sensing signal indicative of current flowing through the power switch with an overlapping signal or jittering a current threshold signal with the overlapping signal, wherein the overlapping signal varies with a first frequency and an enveloping line of the overlapping signal varies with a second frequency, and wherein the first frequency is higher than the second frequency;
• and
• comparing the current sensing signal with the current threshold signal, and turning off the power switch when the current sensing signal is higher than the current threshold signal.