LED drivers offer highest efficiency in smallest PCB area

LED drivers offer highest efficiency in smallest PCB area

The AS3674 and AS3490 LED backlight drivers for smartphone LCD displays are claimed to enable the industry’s best application efficiency at a peak level of 90%, including the dc/dc converter and the current sources. With a PCB footprint of only 11.5 mm², and just four external components required, the drivers are well suited for smartphones and other mobile devices where space is at a premium.

The AS3674 is a highly efficient 2-MHz dc/dc switch mode step-up converter controlling 5 current sources with each driving 2 LEDs in series. The current for the LED channels can be set by an external resistor with a maximum of 25 mA per channel.This part is controlled by two enable inputs which can also serve as PWM inputs between 100 Hz and 800 Hz with 1:2,000 dimming ratio.

The AS3674 operates from a 2.5 to 5.5 V power supply and includes a number of safety features such as under-voltage lockout, overcurrent and over-temperature protection and LED testing. It also includes the startup feature. The AS3490 incorporates the same functionality as the AS3674 but addresses only three LED channels. Both the AS3674 and AS3490 are housed in space saving 12-ball WL-CSP package (1.7 x 1.4 x 0.5 mm, 0.4 mm pitch).(ea/1,000;AS3674,$0.72;AS3490,$64 available now)

By Christina Nickolas

austriamicrosystems , Unetrremstaetten , Austria
U.S. Sales Office 408-345-1790

www.austriamicrosystems.com