ams AS3649 intelligent flash LED driver

ams has launched an intelligent LED driver for mobile phone cameras that maximises the brightness of the flash without causing the phone’s battery to fall below its minimum operating voltage.

The AS3649 LED driver uses a ‘diagnostic pulse’ - a burst of controlled high current lasting a few milliseconds - immediately before every flash operation. During this pulse, the device measures the momentary voltage across the terminals of the phone’s battery. Based on this measurement, it reports a value for the highest flash drive current the battery can sustain, up to a maximum of 2.5 A, avoiding any risk of the phone dropping below its minimum voltage and resetting itself during the main flash.

Drawing on advanced analog sensing technology developed by ams, the AS3649 measures the battery voltage and current with high accuracy, enabling it to precisely calibrate the optimal LED drive current under many conditions.

Mobile phones that use the AS3649 can therefore generate the highest possible level of light for the flash without the need for a bulky auxiliary power source such as a supercapacitor. Users benefit from higher image quality and higher resolution. When taking pictures of fast-moving objects, a brighter flash enables the use of faster shutter speeds for sharper, clearer pictures.

The introduction of the LED driver AS3649 also allows mobile phone manufacturers to reduce the engineering and software development effort involved in flash LED implementation considerably.