Flash LED driver enables brighter, clearer mobile phone images

The AS3649 intelligent LED driver for mobile phone cameras maximizes the brightness of the flash without causing the phone's battery to fall below its minimum operating voltage. The part is an inductive high-efficient dc-dc  step-up converter with two current sources. It operates at a fixed frequency of 4 MHz and can supply up to 2.5 A to a single LED or up to 1.25 A each to two LEDs.

The LED driver uses an innovative “diagnostic pulse” – a burst of controlled high current lasting a few milliseconds – immediately before every flash operation. The device's current-source architecture provides for effective thermal management, and an on-board NTC (temperature sensor) automatically reduces the current to the LED if it exceeds a programmable temperature threshold.

Housed in a WL-CSP package, the AS3649 is controlled by an I2C interface and has a dedicated hardware reset pin. The interface input voltage levels are 1.8-V compliant. Other features include automatic flash timeout timer to protect the LED(s), overvoltage and undervoltage protection, overtemperature protection, and LED short/open circuit protection.  ($0.87 ea/1,000 – available now)