A dynamic step dimming interface is provided that allows a ballast to energize a lamp in a dim mode or a normal mode. The ballast includes a lamp controller that energizes the lamp using an oscillating current. The oscillating current is also provided to a voltage monitor, which indicates the voltage level of the oscillating current, and to a rectifier, which provides an output indicative of the oscillating current. The rectifier is responsive to user input indicating whether the dim mode or the normal mode is to be used. A processing circuit receives the voltage level from the voltage monitor and provides a mode command to the ballast, indicating the lamp mode, based on inputs received, and provides a reference voltage to a comparator. The comparator receives the rectifier output and the reference voltage, and generates a voltage indicative of a power level of the lamp for the processing circuit.