PROGRAMMABLE CURRENT REGULATOR FOR LED HEADLAMP APPLICATIONS

摘要

LED devices are finding their way into more and more applications for illumination in a variety of markets. One interesting use for white LEDs is in an automotive headlamp. These LEDs would need to be high luminous flux output devices implying high power requirements. Since the desirable output parameter is luminous flux and this parameter is dependent on the forward current through the LED, a current regulator circuit is ultimately needed. Further, since the luminous flux output of an LED can vary from manufacturing lot to lot even for a fixed forward current, a scheme to provide programmable output current is desirable to match the circuit for a particular manufacturing lot of LED devices. Also, the programmability allows for such features as dimming.This paper will describe just such a circuit.