Fundamentals of LED Drivers

A typical LED (Light Emitting Diode) based lighting system is shown in Fig. 1. It is composed of a power source such as your regular wall outlet or a battery, an LED driver, an LED or banks of LED’s, and a lamp or fixture. An LED driver is an electronic circuit or component that processes power from the source into power usable by the LED’s. The driver regulates and controls the current supplied to the LED’s. Control or feedback signals can regulate this power to produce various effects on the LED’s. The fixture or lamp processes the light from the LED’s to produce the desired lighting effects. The purpose of this paper is to provide an overview of the technical fundamentals of LED drivers. Initially, some key electrical characteristics of LED’s are reviewed. These characteristics indicate the need to drive LED’s with a controlled current. Temperature dependence and the natural negative temperature coefficient of LED’s provide challenges in current sharing when LED’s are connected in parallel. Series/parallel connection of LED’s provides a possible solution to LED current sharing.