Patent ID: 8686703
Filing Date: 2014-04-01
Classification: H02M

Abstract:
1. A controller used in a switching power supply, wherein the switching power supply comprises a switching circuit having a main switch and configured to provide an output signal, the controller comprises: an oscillator configured to generate a slope compensation signal and a clock signal; a first comparison circuit coupled to the oscillator, wherein the first comparison circuit generates a first comparison signal in accordance with a current sensing signal representative of the current flowing through the main switch, a feedback signal corresponding to the output signal of the switching circuit, and the slope compensation signal; and a logic circuit coupled to the oscillator and the first comparison circuit, wherein based on the clock signal and the first compensation signal, the logic circuit generates a control signal to control the ON and OFF switching of the main switch; wherein if the on time of the main switch is longer than a predetermined time period, the slope compensation signal will have a first slew rate during the predetermined time period and will have a second slew rate outside of the predetermined time period, and wherein the first and the second slew rates are both positive, and the second slew rate is smaller than the first slew rate.