Patent ID: 8488342

Claim:
A system for regulating a power converter, the system comprising: a first signal generator configured to receive a first sensed signal and generate an output signal associated with demagnetization, the first sensed signal being related to a first winding coupled to a secondary winding for a power converter, the secondary winding being associated with at least an output current for the power converter; a ramping signal generator configured to receive the output signal and generate a ramping signal; a first comparator configured to receive the ramping signal and a first threshold signal and generate a first comparison signal based on at least information associated with the ramping signal and the first threshold signal; a second comparator configured to receive a second sensed signal and a second threshold signal and generate a second comparison signal, the second sensed signal being associated with a first current flowing through a primary winding coupled to the secondary winding for the power converter; a second signal generator configured to receive at least the first comparison signal and the second comparison signal and generate a modulation signal; and a gate driver configured to receive the modulation signal and output a drive signal to a switch, the switch being configured to affect the first current flowing through the primary winding; wherein: the output signal is associated with a demagnetization duration; the drive signal is associated with a switching period; and the system is further configured to keep a ratio of the demagnetization duration to the switching period constant.