Patent ID: 7615934
Filing Date: 2009-11-10
Classification: H05B,Y10S

Abstract:
1. A switching circuit for a ballast, comprising: a resonant circuit, having a capacitor and a transformer connected in series to operate a lamp; wherein said transformer has a first winding connected in series with said lamp; a second winding and a third winding of said transformer generate a first control signal and a second control signal in response to a switching current of said resonant circuit; a first transistor, coupled to switch said resonant circuit in response to a first switching signal; a second transistor, coupled to switch said resonant circuit in response to a second switching signal; a first control circuit, coupled to generate said first switching signal in response to said first control signal; a second control circuit, coupled to generate said second switching signal in response to said second control signal; and a charge pump circuit, coupled to said first control circuit to provide a first supply voltage to said first control circuit; wherein said third winding of said transformer is coupled to provide a second supply voltage to said second control circuit; wherein said charge pump circuit is further coupled to said second control circuit.