The present document relates to a method and system for dimming low power illumination devices, such as LED (Light Emitting Diode) assemblies. A controller for a driver circuit of a light source is described. The driver circuit controls a plurality of illumination states of the light source using a power converter, which converts power from an input voltage waveform of a mains power supply into a drive signal for the light source. The controller comprises an event detection unit; a state register to store an indication of a current state of the illumination states; a state processor to determine a target state of the illumination states, based on the detected event and based on the current state; and an output control unit controls the power converter of the driver circuit to provide a drive signal for the target state.