Patent ID: 8811042

Claim:
A system for protecting a power converter, the system comprising: a first comparator configured to receive a sensing signal and a first threshold signal and generate a first comparison signal based on at least information associated with the sensing signal and the first threshold signal, the sensing signal being associated with at least a primary current flowing through a primary winding of the power converter, the power converter being associated with a switching frequency and further including a switch configured to affect the primary current; a timing component configured to receive an input signal and generate a timing signal; and an off-time component configured to receive the timing signal, to detect the first comparison signal at a detection time in response to the timing signal, and to generate an off-time signal based on at least information associated with the first comparison signal if the detection time corresponds to a time when the switch is turned on; wherein the off-time component is further configured to, if the detection time corresponds to the time when the switch is turned on and the detected first comparison signal indicates that the sensing signal to be smaller than the first threshold signal in magnitude, generate the off-time signal to keep the switch to be turned off for at least a predetermined period of time, the predetermined period of time extending beyond at least a beginning of a next switching period corresponding to the switching frequency.