Analog/Power: Single Chip Plays Dual Role In Mobile-Device Cameras

A novel power- and lighting-management IC addresses all lighting functions for cellular phones, PDAs, and digital cameras. The chip also takes on display and sensor bias-supply applications. One 95% efficient charge pump delivers up to 600 mA to drive ultra-bright flash LEDs. A second charge pump helps generate high positive and negative supply voltages: ±15 V at 5 mA for thin-film transistors, or −6 V at 10 mA for organic-LED displays. The flash can be synchronized with an external strobe via a general-purpose input-output (GPIO) input. Other GPIO pins provide access to an internal 10-bit analog-to-digital converter to match the flash to ambient lighting. An on-chip, programmable, dc-dc step-up converter provides up to 40 V at 20 mA to drive as many as eight white LEDs. The same dc-dc converter could also be used to bias CCDs. The AS3681 comes in a 5- by 5-mm QFN32 package and costs $1.50 each in 250,000-piece lots.