Tomi Koskela
National Semiconductor

Color LEDs (light-emitting diodes) are becoming more and more popular in portable consumer devices such as mobile phones, portable media players, and gaming and navigation devices. They have a number of uses, including as indication lights for Short Message Service (SMS) or incoming calls; for personalization of handsets with keypad lighting, fun lighting, and phone cosmetics; and for display backlighting.

The resulting increases in the RGB-LED count on mobile phones create specific challenges for LED drivers. These include issues of power consumption, control interface/programmability, electromagnetic interference (EMI), overall solution size, and system cost. This white paper discusses in detail to two key topics related to driving color LEDs in portable devices: indicator and cosmetic lighting, and display backlighting. Special attention is given to reduced power consumption and to solutions that minimize design size and cost.