High Power, Configurable, Pico-Second LED Driver

This technology is a light-emitting diode (LED) driver capable of driving 190mApp of current through an LED. The driver can drive various kinds of LEDs and multiple LEDs in series with up to a total forward voltage of about 8V. The LED is modulated at a single frequency of 200kHz, but future designs could modulate at 1MHz by substituting slower components with faster components. The driver has two levels of feedback:

1. Nonlinearities in the forward voltage are accounted for and removed in order to achieve a linear output with respect to the driving signal; and
2. A UV enhanced silicon photodiode is used to sense the intensity of the LED while lit and correct for nonlinearities by attenuating the current accordingly.

Background:  

As a result of continuous technological advances that have brought about remarkable performance improvements, light-emitting diodes (LEDs) are increasingly finding applications in traffic lights, automobiles, general-purpose lighting, and liquid-crystal-display (LCD) backlighting. As solid state light sources, LED lighting is poised to replace existing lighting sources such as incandescent and fluorescent lamps in the future since LEDs do not contain mercury, exhibit fast turn-on and dimmability, and long life-time, and require low maintenance. Compared to fluorescent lamps, LEDs can be more easily dimmed either by linear dimming or PWM (pulse-width modulated) dimming. A light-emitting diode (LED) is a semiconductor device that emits light when its p-n junction is forward biased. While the color of the emitted light primarily depends on the composition of the material used, its brightness is directly related to the level of current flowing through the junction. Therefore, it is typically desirable for an LED driver circuit to generate a constant current.

Applications:

• Any current or future devices that use LED technology or may use LED technology in the future (i.e. automobile headlights, displays, etc.)

Advantages:

• Able to control the output of an LED to be more efficient and less prone to failure from overcurrent