Patent ID: 8084956

Claim:
An electronic ballast, comprising: an output voltage value reader which reads a voltage value corresponding to an output of the electronic ballast; a power controller which outputs a signal which controls an amount of power outputted by the electronic ballast in accordance with the voltage value; an external voltage value reader which reads an external voltage value; an operating mode selector which selects one of a trimming mode and a normal mode as an operating mode based on the external voltage value; an internal reference value setter which sets an internal reference value when the trimming mode is selected; a comparator which determines a difference between the voltage value corresponding to the output of the electronic ballast and the internal reference value; and a storage unit, wherein the power controller trims an amount of power outputted by the electronic ballast to a resistor corresponding to an impedance of a High Intensity Discharge (HID) lamp by adjusting the signal based upon the difference; and a result of the signal adjustment is stored in the storage unit.