advertisement Tiny, Efficient High Power LED Camera Flash Solutions for
Cell Phone Applications – Design Note 1009
Keith Szolusha
Introduction
Cell phones and PDAs are approaching the limit for small
form factors, but their feature sets are growing with new
functions such as built-in cameras and even video cameras.
The initial in-phone cameras were basic, low resolution devices with little in the way of usable flash capability. However, cell phone camera resolutions have improved and
sophisticated flash technology is expected to keep pace.
There are two flash technologies used in digital still cameras. The first uses a Xenon flash lamp to provide a very
short, high lumen flash with excellent spectral characteristics. LTC offers Xenon photoflash solutions that are
simple, compact and efficient (see Design Note 345).
The second flash technology uses LEDs. LED solutions hold
the upper hand when simplicity and space is at a premium
and they are the only choice when �torch’ or video-mode
lighting is required. LED flash units fit into spaces where
even the smallest Xenon photoflash cannot. Until recently,
LEDs could not compete with Xenon solutions in light
output and spectral performance, relegating them to the
realm of low resolution (sub 1 megapixel) cameras. However, recent (>10Г—) performance improvements have made LEDs an attractive solution for the now popular 1 megapixel
and higher cell phone cameras.
Linear Technology offers many simple and extremely
compact solutions for driving the latest high-light-output LEDs, including Lumileds Luxeon Flash LEDs. These …