A dimming electronic ballast control provides flash suppression by igniting the
fluorescent lamp at a high power level, and then reducing the power output level
to the appropriate dimming set level. The electronic ballast includes an integrated
circuit that uses closed loop phase control and a VCO to control a switching frequency
of a half bridge, which in turn controls power delivered to the fluorescent lamp.
Current through the half bridge is sensed to provide closed loop control. The current
sense signal is used to provide a high power level in the electronic ballast during
ignition of the lamp, and as a phase detector for the phase control. A rate of
change control circuit controls the speed of adjustment between power level settings,
especially during ignition of the lamp. The electronic ballast provides a wide
linear dimming range with fault detection and flash suppression.