Patent ID: 7868603
Filing Date: 2011-01-11
Classification: H02M,H05B

Abstract:
1. A controller for a switching voltage regulator that receives a supply voltage and generates an output voltage for a load, the controller comprising: an input terminal configured for receiving a feedback signal indicative of an output condition for the switching voltage regulator; an error amplifier configured for generating an error signal based on a comparison of the feedback signal to a reference signal, wherein the reference signal indicates a desired output condition for the switching voltage regulator; a feed-forward circuit configured to receive the error signal from the error amplifier at a first input terminal that is directly coupled to the error amplifier, and a sensed signal indicative of a supply voltage level at a second input terminal that is directly coupled to the supply voltage, wherein the feed-forward circuit generates at an output an adjusted error signal that has a substantially proportional relationship to the error signal and wherein the adjusted error signal output by the feed-forward circuit increases when the sensed signal indicative of the supply voltage level decreases and decreases when the sensed signal indicative of the supply voltage level increases such that the adjusted error signal is adjusted in relation to said received error signal with a substantially inverse relationship to the sensed supply voltage level; and an oscillator configured to generate a periodic ramp voltage whose frequency does not vary based on the adjusted error signal; and a pulse-width modulation comparator configured to receive the adjusted error signal from the output of the inverse feed-forward circuit at a first input terminal, and to receive the periodic ramp voltage from the oscillator at a second input terminal that is directly coupled to the oscillator, wherein the pulse-width modulation comparator is configured to generate a pulse-width modulated output signal based on the adjusted error signal and the periodic ramp voltage, wherein a product of the supply voltage level and duty-cycle of the pulse-width modulated output signal is substantially constant for a given reference signal.