Patent ID: 7652463
Filing Date: 2010-01-26
Classification: H02M

Abstract:
1. A PWM controller for compensating a maximum output power of a power converter, comprising: an oscillator, generating a pulse signal, wherein a switching period of the pulse signal is controlled by a first discharge signal and a second discharge signal, and the first discharge signal is correlated to an amplitude of a feedback signal of the power converter; a control circuit, coupled to the oscillator for generating a PWM signal in response to the pulse signal, wherein the PWM signal controls a power switch; and a frequency modulator, coupled to the oscillator and the control circuit for generating the second discharge signal in response to the PWM signal, wherein a peak value of the second discharge signal is used to modulate a switching period of the PWM signal, and the peak value of the second discharge signal decreases for prolonging the switching period of the PWM signal to achieve an identical output power limit for the low-line and high-line input voltage.