US Patent 7876060 Multi-lamps instant start electronic ballast

The electronic ballast comprises a series half bridge resonant inverter and a control circuit for the inverter with dimming capability. The inverter includes a first and a second voltage feedback circuits including first and a second charge pumps coupled in between inverter output and the dimming input of the control circuit. The feedback circuits generate a reference control signal to control operation after starting and an error control signals when the inverter output voltage exceeds a predetermined value.