AAT2868

PRODUCT DATASHEET AAT2868 SystemPowerTM CABC Compatible 4 Channel Backlight Driver with Dual LDO Regulators General Description The AAT2868 is a low-noise, constant-frequency charge pump DC/DC converter that uses a dual-mode load switch (1x) and fractional (1.5x) conversion to maximize efficiency for white LED Content Adaptive Brightness Control (CABC) applications. The AAT2868 is capable of driving 4 white LEDs at a total 124mA from a 2.7V to 5.5V input. The current sinks may be operated individually or in parallel for driving higher-current LEDs. A low external parts count (two 1μF flying capacitors and two small 1μF capacitors at IN and OUTCP) makes the AAT2868 ideally suited for small battery-powered applications. The AAT2868 also includes two 150mA low dropout (LDO) linear regulators as additional power supplies for display and related camera power. The LDO voltage is also programmable. AnalogicTech’s Advanced Simple Serial Control™ (AS2Cwire™) serial digital input is used to enable, disable and set the maximum LED current to one of 32 levels for the LEDs. The current ranges from 31mA to 0.4mA. An external PWM input is adopted to dim the LED current from 100% to 1% of the maximum LED current by varying the PWM duty cycle with frequencies up to 100kHz. To eliminate flicker or noise associated with PWM control, the input PWM signal is filtered to provide a steady state output current. Each output of the AAT2868 is equipped with built-in protection for short-circuit and au...