General Description
The AAT3143 is a low noise, constant frequency charge pump DC/DC converter that uses a tri-mode load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED applications. The AAT3143 can deliver current levels up to 80mA to drive white LEDs connected to the four current source outputs from a 2.7V to 5.5V input. The current source outputs may source up to 20mA each and 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 VIN and VOUT) makes the AAT3143 ideally suited for small battery-powered applications.

Features
•  Input Voltage Range: 2.7V to 5.5V
•  PWM Brightness Control
•  Tri-Mode 1X, 1.5X, and 2X Charge Pump for Maximum Efficiency and VF Coverage
•  Drives Four Low- or High-VF Type LEDs
•  Up to 20mA LED Current per Channel
•  No Inductors
•  1MHz Switching Frequency
•  Small Application Circuit
•  AutoBias™ Technology
•  IQ <1µA in Shutdown
•  2.85x3.0mm TSOPJW-12 Package

Applications
•  Programmable Current Sources
•  White LED Backlighting
•  White Photo Flash for Digital Still Cameras