Rich Rosen
National Semiconductor

The exponential growth of LED lighting has ushered in a vast selection of integrated circuit devices to provide controlled power to LEDs. No longer acceptable to an energy-conscious world, switched-mode LED drivers have long since replaced power-hungry linear current sources as the standard. Applications from flashlights to stadium scoreboards all require precise control of regulated currents. In many instances, real-time changes in LED output intensity are required. This function is commonly referred to as dimming control. This article describes some basic LED theory and several techniques used to provide dimming control to switched-mode LED drivers.