High-power LED drivers require no external switches

As the latest generation of new LEDs achieves higher levels of power and efficiency, use of these devices extends to new areas, such as flashlights and vehicular applications. High-power LEDs are finding use even in ambient lighting, long the sole province of incandescent bulbs and fluorescent tubes. A current source is the best way to power LEDs. Because most energy sources, including batteries, generators, and industrial mains, look more like voltage sources than current sources, LEDs require that you insert some electronic circuitry between them and the source of power. This article presents a series of circuits based on single-power-IC switching regulators, with efficiency and miniaturization as the main objectives. The circuits' designers approach these objectives by minimizing the use of large components, such as external power transistors, switches, high-value capacitors, and current-sense resistors, and by maintaining regular operation by delivering constant, high-intensity light over as extended a range as possible.