Patent ID: 7218060

Claim:
A flyback ballast, comprising: a transformer, having a first winding, a second winding, and a third winding; a first switch coupled to the first winding of the transformer to form a flyback converter; a first rectifier and a second rectifier coupled to the second winding and the third winding, respectively; a first capacitor coupled to the first rectifier to form a first filter; a second capacitor coupled to the second rectifier to form a second filter; a second switch coupled to the first filter; a third switch coupled to the second filter; and wherein the first filter is coupled to the second filter through a first terminal pair of a lamp, the second switch is coupled to the third switch through a second terminal pair of the lamp, a switching signal is provided to the first switch to control the power of the transformer delivered to the first filter and the second filter, and a second switching signal and a third switching signal are provided to the second switch and the third switch respectively for controlling the power delivered to the lamp.