Austriamicrosystems AS3674/AS3490 LED backlight driver range

Austriamicrosystems has launched the AS3674 and AS3490, two LED backlight drivers for smartphone LCD displays.

The LED drivers enable an efficiency at a peak level of 90%, including the DC-DC converter and the current sources. With a PCB footprint of 11.5 mm² and four external components required, the devices are suitable for smartphones and other mobile devices.

The family complements the company's portfolio of lighting management units which address backlight, smart light and ALS (ambient light sensing) processing inside a single IC. The AS3674 is a 2 MHz DC-DC switch mode step-up converter controlling five current sources, with each driving two LEDs in series.

For added flexibility, the current for the LED channels can be set by an external resistor, with a maximum of 25 mA per channel. The AS3490 incorporates the same functionality as the AS3674 but addresses only three LED channels.

A soft startup feature allows the AS3674 to be integrated into noise-sensitive RF systems. It is controlled by two enable inputs which can also serve as PWM inputs between 100 and 800 Hz with a 1:2000 dimming ratio. The two-LED-per-channel configuration, combined with the 2 MHz operating frequency of the converter, allow the use of external components such as a 4.7 µH coil. This results in a claimed 6% higher efficiency than other drivers.

The AS3674 operates from a 2.5 to 5.5 V supply and includes a number of safety features such as undervoltage lockout, overcurrent and overtemperature protection and LED testing.