Patent ID: 7230391

Claim:
A ballast circuit for powering a lamp, said ballast circuit comprising: a first rectifier circuit connected to a first alternating current (AC) source and generating a first direct current (DC) input power signal; a second rectifier circuit connected to a second AC source and generating a second DC input power signal; a first switching circuit connected to the first rectifier circuit for receiving the first DC input power signal, said first switching circuit generating a first DC output power signal as a function of the first DC input power signal; a second switching circuit connected to the second rectifier circuit for receiving the second DC input power signal, said second switching circuit generating a second DC output power signal as a function of the second DC input power signal; a dimming regulation circuit for generating a dim level command signal as a function of whether power is being supplied by each of the first and second AC sources to the lamp; and an inverter circuit coupled between the first and second switching circuits and the lamp, said inverter circuit responsive to the dimming regulation circuit to control an amount of power being provided to the lamp as a function of the dim level command signal.