General Description
The AAT3159 is a low noise, constant frequency charge pump DC/DC converter that uses a tri-mode load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED applications. The device is capable of driving up to four channels of LEDs at up to 40mA per channel from a 2.7V to 5.5V input supply voltage. The current sinks may be operated individually or in parallel for driving higher-current LEDs. A low external parts count (two 1μF flying capacitors [C1 and C2] and two small 1μF capacitors [CIN and COUT]) makes this part ideally suited for small battery-powered applications.

FEATUREs
• Input Supply Voltage Range: 2.7V to 5.5V
• Tri-Mode (1X/1.5X/2X) Charge Pump
    • Maximizes Efficiency
    • 1MHz Constant Switching Frequency
    • No Inductors, Low Noise Operation
• Drives Four Channels of LEDs up to 40mA/ Channel
• User-Programmable LED Current
• Excellent LED Channel-to-Channel Current Matching
• Digitally Programmable LED Current with Single-Wire S2Cwire Interface
    • 16 Current Levels From 40mA to 50μA
• Low IQ (50μA) for Low Current Mode Operation
• True Load Disconnect in Shutdown; IQ < 1μA
• Built-In Thermal Protection
• Built-In Auto-Disable for Open LED Circuit
• Automatic Soft-Start Minimizes Inrush Startup Current
• 2.85x3x1mm TSOPJW-14 Package

APPLICATIONs
• Cellphones, DSC, Handheld Devices
• LED Photo Flash
• Programmable Current Sinks
• White LED Backlighting