Patent ID: 7453251

Claim:
A control circuit for a pulse width modulation (PWM) switching power regulator which converts an input voltage to an output voltage, comprising: an error amplifier having a first input receiving a first reference signal, a second input receiving an output sense signal, and an output providing a compensation signal used to control PWM switching of the PWM switching power regulator; a transconductance amplifier having an inverting input, a first non-inverting input receiving a ratio-metric tracking signal based on the input voltage a second non-inverting input receiving a second reference signal and an output coupled to said inverting input and providing said first reference signal to said input of said error amplifier; wherein said transconductance amplifier drives the first reference signal based on whichever of said second reference signal and said ratio-metric tracking signal has a lower voltage level; and a capacitor coupled to said output of said transconductance amplifier.