A software controlled electronic dimming ballast for preheating, striking,
and varying the dimming level of a lamp. In one embodiment, the ballast
includes an EMI filter circuit, an AC/DC converter circuit, a PFC
circuit, an inverter circuit, and a software controlled microcontroller
circuit. The microcontroller circuit includes a microcontroller and
software for generating inverter control signals that cause the inverter
circuit to preheat, strike, and varying the dimming level of the lamp.
The inverter control signals are generated based on dimming control and
lamp dimming level feedback signals. The ballast also includes a lamp
dimming level feedback signal conditioning circuit for generating the
lamp dimming level feedback signals. Alternative embodiments of the
ballast are also described.