Patent ID: 7940037
Filing Date: 2011-05-10
Classification: H05B

Abstract:
1. An electronic device comprising a driver for light emitting semiconductor devices, the driver comprising: a first MOS transistor coupled with a channel to the light emitting semiconductor device at an output node; the first MOS transistor being configured to determine a current through the light emitting semiconductor device; a control loop configured and adapted to control the first MOS transistor to maintain the magnitude of the current through the light emitting semiconductor device at a target value when a voltage drop across the first MOS transistor changes; a second MOS transistor coupled to the output node and biased so as to supply an auxiliary current to the output node, when the voltage drop across the first MOS transistor drops below a minimum voltage level; and a feedback loop configured and adapted to reduce the current to be fed through the light emitting semiconductor device by an amount proportional to the auxiliary current.