Dario Nurzad
National Semiconductor

Availability of handsets with high-resolution complementary metal"oxide"semiconductor (CMOS) cameras (two mega-pixels and above) has caused a migration to high-performance flash modules to allow users to take decent pictures in low light conditions. One option is using high-current white Light-emitting diodes (LEDs), which are a very popular solution because of their low cost, long life, small size, ability to provide continuous light for video applications, and operation at lower voltages than Xenon tubes.

This paper describes the implementation of a flash LED driver, ennumerating its various performance tradeoffs and using National's LM2754 as an example. It also addresses efficiency, thermal management, safety issues, and ways to reduce peak input current.