General Description
The AAT3123/23A/24 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 applications. The device can be used to produce current levels up to 20mA to drive up to six LEDs from a 2.7V to 5.5V input. Outputs may be operated individually or paralleled for driving higher-current LEDs. A low external parts count (two 1µF flying capacitors and two small 1µF capacitors at VIN and OUT) make the AAT3123/23A/24 ideally suited for small battery-powered applications.

FEATUREs
• VIN Range: 2.7V to 5.5V
• Dual Mode 1X and 1.5X Charge Pump for Maximum Efficiency
• Drives Low-VF and High-VF Type LEDs
• Up to Six 20mA Outputs (AAT3124)
• Up to Four 20mA Outputs (AAT3123/23A)
• 32-Position Logarithmic Scale with Digital Control
• Simple Serial Control (S2Cwire) Interface
• Low Noise Constant Frequency Operation
• 1MHz Switching Frequency
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• I Q <1µA in Shutdown
• Temperature Range: -40°C to +85°C
• 12-Pin TSOPJW Package (AAT3123/23A)
• 16-Pin 4x4mm QFN Package (AAT3124)

APPLICATIONs
• Color (RGB) Lighting
• Programmable Current Source
• White LED Backlighting
• White Photo Flash for DSCs