Patent ID: 9577536
Date: 2017-02-21
CPC Classifications: H02H,H02M

Claim:
1. A system controller for protecting a power converter, the system controller comprising: a first controller terminal configured to output a drive signal to a switch to affect a first current flowing through a primary winding of a power converter, the power converter further including a secondary winding coupled to the primary winding, the drive signal being associated with one or more switching periods; and a second controller terminal configured to receive a sensing voltage from a sensing resistor, the sensing voltage representing a magnitude of the first current flowing through the primary winding of the power converter; wherein the system controller is configured to: wherein the current threshold is equal to a first ratio multiplied by a second ratio, the first ratio being equal to a first number of turns of the primary winding divided by a second number of turns of the secondary winding, the second ratio being equal to the reference voltage divided by a resistance of the sensing resistor.