AAT3123

AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications 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. AnalogicTech’s Simple Serial Control™ (S2Cwire™) interface is used to enable, disable, and set the LED drive current with a 32-level logarithmic scale LED brightness control. The AAT3123/23A/24 has a thermal management system to protect the device in the event of a short-circuit condition at the output pin. Built-in soft-start circuitry prevents excessive inrush current during start-up. A high charge pump switching frequency enables the use of very small external capacitors. A low-current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1µA. The device also integrates a test current/auto-disable feature for each channel. The AAT3123/23A is available in a very small, Pb-free 12-pin TSOPJW package. The six output AAT3124 is available in a Pb-free 16-pin 4x4mm QFN package. Features • • • • • • • • • • • • • • • • • ChargePump™ 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 IQ