Patent ID: 7528554

Claim:
An electronic dimming ballast for driving a gas discharge lamp, the electronic ballast comprising: a rectifier operable to receive an AC input voltage from an AC supply and to produce a rectified voltage having a peak magnitude; a boost converter operable to receive the rectified voltage and to produce a substantially DC bus voltage having a DC magnitude greater than the peak magnitude of the rectified voltage, the boost converter operable to operate in critical conduction mode; an inverter operable to convert the DC bus voltage to a high-frequency AC output voltage to drive the lamp; and a control circuit operable to receive a desired light level signal representative of a desired intensity of the lamp, and to provide a first control signal to the inverter and a second control signal to the boost converter; wherein the boost converter is operable to operate in discontinuous conduction mode when the desired intensity of the lamp is below a first threshold intensity.