CPC H02M 3/158 (2013.01) [H02M 1/0041 (2021.05)] | 23 Claims |
1. A control circuit for a switching converter, wherein:
a) in a first operation state, the control circuit is configured to control a switching period of the switching converter to remain unchanged, to control a turn-on time of a power transistor in the switching converter to be not less than a minimum turn-on time in each switching period, and to control a turn-off time of the power transistor to be not less than a minimum turn-off time,
b) in a second operation state, the control circuit is configured to control the turn-on time of the power transistor to be the minimum turn-on time in each switching period, and to adjust the switching period to further reduce a duty cycle;
c) in a third operation state, the control circuit is configured to control the turn-off time of the power transistor to be the minimum turn-off time in each switching period, and to adjust the switching period to further increase the duty cycle;
d) the control circuit comprises a feedback control circuit configured to control the power transistor to be turned on according to a compensation signal and a current sampling signal representing an inductor current of the switching converter, and to control the power transistor to be turned off according to the compensation signal and the current sampling signal, wherein the compensation signal is generated based on an error of a feedback signal representing an output voltage of the switching converter and a reference signal;
e) the feedback control circuit comprises a current control circuit configured to compensate for the error between the feedback signal and the reference signal to generate the compensation signal, and to generate first and second comparison signals by comparing the compensation signal against the current sampling signal; and
f) the feedback control circuit comprises a pulse-width modulation (PWM) generation circuit configured to generate a switching control signal to control the power transistor to be turned on and off according to the first comparison signal, the second comparison signal, the clock signal, the minimum turn-on time, and the minimum turn-off time.
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