Patent ID: 8324827

Claim:
A control circuit for an electronic ballast operable to receive ballast input power and to receive an outboard dedicated dimming signal comprising: a power sensing circuit, the power sensing circuit generating a sensed power signal in response to the ballast input power; an on-time converter, the on-time converter generating an on-time signal in response to the sensed power signal; a dedicated dimming interface, the dedicated dimming interface being operable to generate a dedicated dimming signal in response to an outboard dedicated dimming signal; and a microprocessor, the microprocessor having a first input connected to receive the on-time signal, and having a second input connected to receive the dedicated dimming signal, the microprocessor being configured to detect whether the ballast input power is phase cut power in response to the on-time signal, and being further configured to detect whether a first dedicated dimmer is present in response to the dedicated dimming signal, and being still further configured to generate a dimming control signal in response to at least one of the on-time signal and the dedicated dimming signal; wherein the microprocessor controls the dimming control signal in response to the on-time signal when mains power is phase cut power.