Patent ID: 7813151

Claim:
A variable-mode converter control circuit for a power converter comprising: an oscillating unit, configured to generate a pulse signal and triangle-wave signal of a certain frequency; a switching control signal output unit, configured to output a switching control signal to control an ON/OFF of a plurality of switching devices based on a duty ratio determined from a feedback signal, which is applied to a feedback terminal synchronously with the pulse signal of the oscillating unit; a mode select signal generator, configured to generate a mode select signal for a determination of a control mode of the converter in response to the feedback signal applied to the feedback terminal, wherein the control mode is either a frequency control mode or a duty ratio control mode; a mode selecting unit, configured to select one of the frequency control mode or the duty ratio control mode as the control mode of the converter in response to the mode select signal; and a configuration terminal, wherein the converter is configured to operate in the frequency control mode when the feedback signal is inputted to the configuration terminal; wherein the configuration terminal comprises an RT terminal, the converter further comprising: a resistor, connected to the RT terminal, so that a switching frequency is determined based on the amount of current flowing through the RT terminal; and a capacitor, connected to a CT terminal, so that the switching frequency is determined based on the capacitance.