New white LED Driver From Analog Devices For Camera-Phone Flash

Analog Devices, Inc., a global leader in signal processing technologies and high-performance semiconductors for digital cameras, is launching a white LED driver for camera-phone flash.

The driver uses a new portable power management technique, which maintains picture quality even when the battery power is limited by the demands of multiple phone functions operating simultaneously. An output current power management feature reduces battery-current overstress when the camera flash is activated at the same time the phone is receiving an RF (radio frequency) signal.

Under normal operating conditions the new ADP1653 high-efficiency, high-brightness, dual, white LED driver provides a brighter camera flash than single or low-efficiency white LED drivers. This gives significantly better picture quality in low-light conditions. The light level required to take good-quality photos is significantly increased in camera phones of two Megapixels or higher.

In camera phones, efficiency and system sequencing can be utilised to minimise battery-current overstress. Existing charge pump solutions have a power efficiency rating as low as 40 percent under low battery voltage conditions.

This means that less than half of the input power is converted to output power, thereby further draining the battery. The power efficiency of the ADP1653 peaks at 92 percent and is typically greater than 80 percent over the full voltage range of a Lithium-ion battery.

The ADP1653 also features a logic-input pin which reduces the white LED current to its lowest operation level in less than 50 microseconds when the phone activates the power amplifier to send an RF transmission. This current sequencing technology further extends battery life without compromising photo image quality.

The ADP1653 will be available in volume production in February 2007.