An integrated control circuit for a resonant power converter includes a minimum-frequency programming circuit connected a first resistor to program a minimum switching frequency of the power converter. A feedback circuit is coupled to a feedback terminal to receive a feedback signal for generating an adjustment signal. A maximum-frequency programming circuit connects a second resistor to determine a maximum switching frequency in response to the adjustment signal. An oscillator is coupled to the minimum-frequency programming circuit and the maximum-frequency programming circuit to generate an oscillation signal for determining the switching frequency of the power converter. A feed-forward circuit is connected to a feed-forward terminal to receive a feed-forward signal represents the input voltage of the power converter. The switching frequency is increased in response to decrease of the feedback signal, and the switching frequency is increased in response to the increase of the feed-forward signal.