700 mA flash LED driver

Austriamicrosystems has launched the AS3685, an ultra-small, safe, simple and fully integrated 700 mA charge-pump-based flash LED driver.

The AS3685, claimed to be the world's smallest fully integrated flash LED driver, has 700 mA flash current and is targeted at camera flash applications in mobile phones.

The device's smart charge-pump architecture avoids large spikes at the battery terminals, providing good EMC performance.

To avoid excessive current being drawn from the battery if the phone's power amplifier becomes active while a picture is being taken - a situation potentially causing the phone to shut down due to a related voltage drop - the device can reduce the flash current within a microsecond. This prevents dropped calls.

Other safety features include a built-in flash LED time-out function that guarantees flash shutdown via a built-in factory-programmable timer, typically 800 ms. This prevents the destruction of the LED or damage to the mobile phone from excessive heat produced by the LED.

The driver is supplied with a multimode, two pin interface incorporating off indicator, flashlight and flash operating modes. Variants feature a single-wire interface allowing the flash current to be set in any of 18 different steps depending on actual operating and environmental conditions. This allows it to dynamically reduce the flash current during MP3 playback or at low battery conditions, extending battery life.