May 13 2008
Advanced Analogic Technologies, Inc., a developer of power management semiconductors for mobile consumer electronic devices, announced today the AAT3102 and AAT3103 constant frequency, charge-pump-based, current source white LED (WLED) drivers. Designed to backlight lower-cost LCD displays in entry-level and reduced feature set cell phones, the two new devices help reduce system costs by using a small 2x2.1-mm package while requiring only two external components.
"Most entry-level cell phones targeted at today's rapidly growing emerging markets typically offer very basic lighting features including a small monochrome TFT-LCD panel and minimal accessory lighting," says Phil Dewsbury, product line director for AnalogicTech. "The new current-sourced AAT3102 and AAT3103 deliver up to 30 mA 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."
High Efficiency Charge Pumps
Both new WLED drivers are current-sourced devices designed for applications where an LED cathode is connected to ground. To ensure high readability in lower-cost, more opaque LCD panels, the AAT3102 drives two LEDs at up to 30 mA each. The AAT3103 drives up to three LEDs at up to 30 mA each. The charge pumps in each driver automatically switch between 1X and 2X mode to maintain high efficiency. Both new WLED drivers offer current accuracy of better than 10 percent. Channel-to-channel current matching exceeds 3 percent.
LEDs can be programmed using either a traditional PWM-compatible interface, up to 50kHz or via AnalogicTech's proprietary single-wire S(2)Cwire interface. Using the S(2)Cwire interface, designers can program each WLED over 16-, or 8- 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 from IN and reduces quiescent current to < 1uA. They also feature built-in automatic soft start, and integrated thermal and short circuit protection.
Price and Availability
Both of the new devices are qualified across the -40 degrees C to +85 degrees C temperature range and come in a compact 2 x 2.1-mm SC70JW-10 package. The AAT3102 sells for $0.52 in 1K quantities, while the AAT3103 sells for $ 0.52 in 1K quantities.