An effective LED dimming approach

Abstract

As light emitting diodes (LEDs) have become increasingly accepted as a light source in many applications, the demand for dimming LEDs has also increased. Typically LEDs are supplied with voltage source. Dimming is accomplished by adjusting the average current in the LEDs through pulse width modulation of a switch in series with the load. This paper proposes a technique that uses a current source as the base supply. The average current is adjusted with a switch in parallel to the load. This circuit is shown to be effective in increasing the dimming range of the LEDs.