Patent ID: 8331116

Claim:
A control circuit for use in a power converter, the control circuit comprising: a pulse width modulator coupled to generate a pulse width modulation signal in response to a feedback signal; a logic circuit coupled to turn a switch on and off to regulate an output of the power converter in response to the pulse width modulation signal; and a saturation prevention circuit coupled to the logic circuit to assert a first signal when a first integral value of an input voltage of the power converter reaches a first threshold value and to assert a second signal after a delay time that begins when a difference between the first integral value and a second integral value of a reset voltage of a transformer of the power converter falls to a second threshold value, wherein the logic circuits are adapted to turn off the switch when the first signal is asserted, and to allow the switch to turn on and off in accordance with the pulse width modulation signal when the second signal is asserted.