Current-sourced WLED drivers address lighting needs of entry-level cell phone market

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. 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 lower-cost, more 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 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 S2Cwire interface. Using the S2Cwire 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 1microfarad 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 < 1microamp. They also feature built-in automatic soft start, and integrated thermal and short circuit protection.

Both of the devices are qualified across the -40 to +85 degrees C temperature range and come in a compact 2 x 2.1mm SC70JW-10 package.