Patent ID: 8274801
Filing Date: 2012-09-25
Classification: H02M,Y02B

Abstract:
1. A switching mode power supply comprising: a feedback network configured to provide a feedback signal based on a load condition; a control circuit operatively coupled to the feedback network to receive the feedback signal, wherein the control circuit compares the value of the feedback signal to a threshold value to indicate a light load condition or a normal load condition, the control circuit controls the switching mode power supply to operate in a burst mode for the light load condition, and wherein the control circuit comprises: a current detecting circuit module configured to detect the current flowing through a switch to generate a current detecting signal; a burst-mode controller coupled to the feedback network to receive the feedback signal, wherein based on the feedback signal, the burst-mode controller generates a low frequency modulation signal, and wherein the frequency of the low frequency modulation signal is fixed; a high frequency pulse signal generator coupled to receive the feedback signal and the current detecting signal, wherein based on the feedback signal and the current detecting signal, the high frequency pulse signal generator generates a high frequency pulse signal; and a modulation circuit coupled to the burst-mode controller and the high frequency pulse signal generator to receive the high frequency pulse signal and the low frequency modulation signal, wherein based on the high frequency pulse signal and the low frequency modulation signal, the modulation circuit generates a switch controlling signal to control the switch.