General Description

The AAT3156 is a low noise, constant frequency charge pump DC/DC converter that uses a trimode load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED applications. The AAT3156 is capable of driving six-channel LEDs at a total of 180mA 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 VIN and VOUT) make this part ideally suited for small battery-powered applications.

Features

• VIN Range: 2.7V to 5.5V

• Fully Programmable Current with Single Wire

— 16-Step Logarithmic Scale

— 15/20/30mA Max Current

— Four Low Current Settings Down to 50µA

— Low IQ (50µA) for Low Current Mode

• Tri-Mode 1X, 1.5X, and 2X Charge Pump for Maximum Efficiency and VF Coverage

• Drives Six Channels of LEDs

• Individual Main/Sub-Group Control

• No Inductors, Low Noise Operation

• 1MHz Constant Switching Frequency

• Small Application Circuit

• Built-In Thermal Protection

• Built-In Auto-Disable For Open Circuit

• Automatic Soft-Start

• IQ <1µA in Shutdown

• Thermally-Enhanced QFN44-16 Package

Applications

• Color (RGB) Lighting

• Programmable Current Sinks

• White LED Backlighting

• White Photo Flash for DSCs