Patent ID: 7414372

Claim:
A dimming ballast control circuit for driving a ballast power switching circuit powering a gas discharge lamp comprising: a driver circuit for driving high and low side switches of the ballast power switching circuit; a control circuit for driving the driver circuit including an oscillator circuit for providing an oscillating signal to control the frequency of operation of the ballast power switching circuit, the ballast power switching circuit outputting lamp powering pulsed signals; and a dimming control circuit having an input, the dimming control circuit receiving an AC lamp current feedback signal at the input, the dimming control circuit further receiving a DC input voltage reference at the input whereby the DC input voltage reference determines a desired dimming level of the lamp and the AC lamp current feedback signal maintains the lamp brightness at the desired dimming level, wherein said AC lamp current signal is superimposed on said DC input voltage reference at the input to provide a time varying signal having a DC level.