A switching circuit for a power converter includes an oscillation circuit, a first circuit, and a first comparator. The oscillation circuit generates a switching signal for regulating an output of the power converter. The first circuit generates a threshold signal. The first comparator is coupled to receive a signal representative of a current through a power switch. Besides, the first comparator generates a control signal in response to the signal and the threshold signal. A frequency of the switching signal is increased in response to the enabling of the control signal.