Patent ID: 8085027

Claim:
A switch-mode power conversion system, the system comprising: a primary winding configured to receive an input voltage; a secondary winding coupled to the primary winding and configured to, with one or more other components, generate an output signal; a feedback component configured to receive the output signal and generate a feedback signal based on at least information associated with the output signal; a voltage detector configured to receive the input voltage and output a detection signal; a mode controller configured to receive the detection signal and the feedback signal and generate a switch signal based on at least information associated with the detection signal and the feedback signal; and a switch configured to receive the switch signal and affect a first current flowing through the primary winding; wherein the mode controller is further configured to: process information associated with the detection signal and a first threshold; determine whether the detection signal and the first threshold satisfy a first predetermined criterion; process information associated with the feedback signal and a second threshold; determine whether the feedback signal and the second threshold satisfy a second predetermined criterion; determine whether an operation mode for the switch-mode power conversion system is a quasi-resonant mode based on at least whether the first predetermined criterion is determined to be satisfied and whether the second predetermined criterion is determined to be satisfied; determine whether the operation mode is a fixed frequency mode based on at least whether the first predetermined criterion is determined to be satisfied and whether the second predetermined criterion is determined to be satisfied; process information associated with the feedback signal, the second threshold, and a third threshold; determine whether the feedback signal, the second threshold, and the third threshold satisfy a third predetermined criterion; and determine whether the operation mode is a quasi-resonant foldback mode based on at least whether the third predetermined criterion is determined to be satisfied, the quasi-resonant foldback mode being different from the quasi-resonant mode; wherein the switch signal corresponds to the operation mode for the switch-mode power conversion system.