austriamicrosystems (AMS), a designer and producer of analog ICs, has launched the AS3490 and AS3674 LED backlight drivers that are suitable for smartphone LCD displays. These drivers have a peak level efficacy of 90% with DC-DC converter.
AS3674 Smartphone LCD Backlight LED Driver Block Diagram
The driver needs only four external parts and has an 11.5 mm² PCB footprint. They are suitable for mobiles including smartphones, which require minimal space.
Ambient light sensing (ALS) process in an IC, backlight and smart light can be achieved by the AS3674 backlight driver. The AS3674 acts as a MHz DC-DC switch mode step-up converter, which controls five current sources and powers two LEDs in a sequence. Small external parts, including 4.7 µH coil, have been used in this driver which yields better performance.
In addition, the electrical power can be increased up to 25 mA per LED channel by using an exterior resistor. The AS3490 exhibits similar performance; however, it can only address three channels.
The AS3674, with a typical soft start up, can be inserted easily into RF systems, which are sensitive to noise. Further, the driver acts as PWM inputs within 100 to 800 Hz at 1:2000 dimming ratio.
With a power supply requirement of 2.5 V to 5.5 V and other safety characteristics like LED analysis, over temperature and over current protection and low voltage lockout, the AS3674 performs efficiently. Both the drivers have been placed in a 12-ball WL-CSP package (1.7x1.4x0.5 mm, 0.4 mm pitch), which save space.
The Senior Marketing Manager of Illumination from AMS, Ronald Tingl stated that smartphones have become minute computers that require power with big displays. However, producers find it difficult to develop smartphones with extended battery life and reduced size. The AS3674 fulfills these two criteria with minimum area of PCB. The entire PCB area requisite is comparatively 60% less.
Source: http://www.austriamicrosystems.com