Patent ID: 8634212

Claim:
A controller for a power converter, comprising: a sense current integrating circuit, for integrating a sense current representative of a conduction current flowing through a power switch of the power converter to directly obtain a first integrating result; a reference current integrating circuit, for performing an integrating operation to a reference current to thereby obtain a second integrating result; and a drive signal generation circuit, for using a relative magnitude relationship between the first integrating result and the second integrating result cooperative with a status of an output voltage of the power converter to determine a switching period of the power switch; wherein the drive signal generation circuit comprises: a first comparator, for comparing the first integrating result with the second integrating result to thereby output a first comparison result representative of the relative magnitude relationship between the first integrating result and the second integrating result; a second comparator, for comparing an output voltage error signal with a reference voltage to thereby output a second comparison result representative of the status of the output voltage; an AND gate, for performing a logic AND operation to the first comparison result and the second comparison result to generate a trigger signal for determining a moment of switching on the power switch and a moment of resetting the sense current integrating circuit and the reference current integrating circuit and thereby determining the switching period of the power switch; a third comparator, for comparing a sense voltage signal proportional to the conduction current and a preset peak voltage to thereby output a third comparison result for determining a moment of switching off the power switch; a flip-flop, for generating a drive signal according to the trigger signal and the third comparison result to switch ON and OFF states of the power switch; and a one-shot pulse generation circuit, for generating a one-shot pulse according to the drive signal to reset the sense current integrating circuit and the reference current integrating circuit; wherein the flip-flop is an S-R type flip-flop, a set terminal of the S-R type flip-flop is electrically coupled to receive the trigger signal, and a reset terminal of the S-R type flip-flop is electrically coupled to receive the third comparison result.