AAT3167

High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications General Description The AAT3167 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 AAT3167 is capable of driving five LEDs for a total of 135mA 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 IN and OUTCP) make this part ideally suited for small, battery-powered applications. AnalogicTech's AS2Cwire™ (Advanced Simple Serial Control™) serial digital input is used to enable, disable, and set current for each LED with a 16-level logarithmic scale plus four low-current settings down to 115µA. For optimized efficiency, low-current settings require only 50µA of housekeeping current. Each output of the AAT3167 is equipped with builtin protection for output short circuit and auto-disable for load short-circuit conditions. Built-in softstart circuitry prevents excessive inrush current during start-up. A low-current shutdown feature disconnects the load from the input and reduces quiescent current to less than 1µA. The AAT3167 is available in a Pb-free, space-saving, thermally-enhanced, 14-pin 3x3mm STDFN or 16-pin 4x4mm QFN package and is rated over the -40°C to +85°C temperature range. AAT3167 Features • • ChargePump™ • • • • • • • • • • • VIN Range: 2.7V to 5.5V Fully Programmable Current with Single Wire — 16-Step Logarithmic Scale — 14/18/27mA Max Current — Four Low-Current Settings Down to 115µA — Low IQ (50µA) for Single-Channel, LowCurrent Mode Tri-Mode 1X, 1.5X, 2X Charge Pump for Maximum Efficiency and VF Coverage Drives Up to Five LEDs Individual Main-Sub (4-1) 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