Product category:
Power Supply ICs and Controllers
News Release from: Advanced Analogic Technologies | Subject: AAT3102 and AAT3103
Edited by the Electronicstalk Editorial
Team on 19 May 2008
Charge pumps power budget backlights
Two new devices help reduce system costs for backlighting low-quality LCDs in low-cost handsets.
The AAT3102 and AAT3103 are constant-frequency charge-pump-based current source white LED (WLED) drivers available now from AnalogicTech Designed to backlight lower-cost LCDs in low-cost handsets, the two new devices help reduce system costs by using a small 2 x 2.1mm package and requiring only two external components
This article was originally published on Electronicstalk on 19 Sep 2008 at 8.00am (UK)
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Most entry-level cellphones for emerging markets typically offer very basic lighting features including a small monochrome TFT-LCD panel and minimal accessory lighting.
The current-sourced AAT3102 and AAT3103 deliver up to 30mA per channel to allow designers to cost-effectively build systems that provide high readability with these low cost panels, while keeping system costs low by using small packages and a minimal number of external components.
Both new WLED drivers are current-sourced devices designed for applications where an LED cathode is connected to ground.
To ensure high readability in low-cost opaque LCD panels, the AAT3102 drives two LEDs at up to 30mA each.
The AAT3103 drives up to three LEDs at up to 30mA each.
The charge pumps in each driver automatically switch between 1x and 2x mode to maintain high efficiency.
Both WLED drivers offer current accuracy of better than 10%, and channel-to-channel current matching is better than 3%.
LEDs can be programmed using either a traditional PWM-compatible interface, up to 50kHz or via AnalogicTech's proprietary single-wire S2Cwire interface.
Using the S2Cwire interface, designers can program each WLED over eight or 16 steps.
To keep solution size small and affordable, the new drivers only require two external devices: a 1uF capacitor for the charge pump and an external resistor to set full-scale LED current.
The AAT3102 and AAT3103 also offer a low-shutdown current feature which disconnects the load and reduces quiescent current to less than 1uA.
They also feature built-in automatic soft start, and both thermal and short-circuit protection.
Both devices are qualified across the -40 to +85C temperature range and come in compact 2 x 2.1mm SC70JW-10 packages.
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