General Description

The AAT3151B is a low noise, constant frequency charge pump DC/DC converter that uses a dual mode load switch (1X) and fractional (1.5X) charge pump conversion to maximize efficiency for white LED applications. The AAT3151B is capable of driving four white LEDs at a total of 120mA 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) makes the AAT3151B 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

• Dual Mode 1X and 1.5X Charge Pump for Maximum Efficiency and VF Coverage

• Drives Four Channels of LEDs

• No Inductors, Low Noise Operation

• 1MHz Constant Switching Frequency

• Small Application Circuit

• Built-In Thermal Protection

• Built-In Auto-Disable for Short-Circuit

• Automatic Soft Start

• IQ <1μA in Shutdown

• TDFN33-12 Package

Applications

• Color (RGB) Lighting

• Programmable Current Sinks

• White LED Backlighting

• White Photo Flash for Digital Still Cameras