Patent ID: 8824173

Claim:
A system controller for regulating a power conversion system, the system controller comprising: a first controller terminal; a second controller terminal; a first switch; and a third controller terminal; wherein the system controller is configured to: generate a drive signal at the first controller terminal to turn on or off a second switch to adjust a primary current flowing through a primary winding of the power conversion system; receive a first signal at the second controller terminal from the second switch; and generate a detection signal associated with a demagnetization process of the primary winding of the power conversion system based on at least information associated with the first signal; wherein the first switch is configured to receive the first signal at the second controller terminal and a current sensing signal at the third controller terminal and be turned on or off based on at least information associated with the drive signal, the current sensing signal being associated with the primary current flowing through the primary winding of the power conversion system.