LED Driver Features Serial Brightness Control

Advanced Analogic Technologies’ AAT1231 is a high frequency, high efficiency inductive boost dc-dc converter for controlling white LEDs in portable systems operating from single-cell lithium-ion/polymer batteries. Delivering 50 mA up to 24 V, this device is capable of driving up to six white LEDs in series or up to 12 white LEDs in a parallel/series configuration using AnalogicTech’s digital Simple Serial Control (S²Cwire) single-wire interface.

LED output current on the AAT1231 is controlled in 16 linear steps. By changing the feedback voltage with the SEL pin, designers can ‘set and forget’ the output across a total of 26 steps (after overlap) from 7.5% to 100%. Digital control improves display readability by providing constant flicker-free LED output.

The device’s high 2-MHz switching frequency provides fast response to load transients and permits the use of small external components including a 2.2-µH inductor. Overall efficiency is up to 82%.

The device also adds a true load disconnect feature which completely isolates the load from the power source. This function reduces leakage current to less than 1 µA.

The AAT1231 is immediately available in a 12-pin TSOPJW package. The device sells for $0.94 each in 1000-piece quantities.