Patent ID: 8847516

Claim:
A device comprising: a power supply; a light emitting device electrically coupled between the power supply and a reference node, wherein the light emitting device defines a node; a control element in a current shunting path electrically coupled in parallel with the light emitting device between the power supply and the reference node, wherein the control element is configured to control a voltage drop across the current shunting path responsive to an electrical signal from the node of the light emitting device, wherein the control element comprises a regulating transistor and wherein a control electrode of the regulating transistor is electrically coupled to the node of the light emitting device; a switching transistor electrically coupled in series with the regulating transistor in the current shunting path between the power supply and the reference node; and a controller coupled to a control electrode of the switching transistor, wherein the controller is configured to generate a pulse width modulated control signal that is applied to the control electrode of the switching transistor to vary a current though the current shunting path.