A method of operating a lamp that has a power controller connected between a terminal and a light emitting element that converts the line voltage to an RMS load voltage. An input to an analog control block is provided in the controller that is independent of a change in magnitude of the line voltage. A trigger signal from the analog control block is provided at a first frequency by charging and discharging a capacitor in the analog control block that receives the input. An initial condition of the analog control block is resetted periodically. A sync signal synchronizes the trigger signal with a waveform of the line voltage. A load voltage is clipped based on the synchronized trigger signal to define the RMS load voltage.