General Description
The AAT1149B SwitchReg is a 2.2MHz step-down converter with an input voltage range of 2.2V to 5.5V. It is optimized to react quickly to load variations and operate with a tiny 0603 inductor that is only 1mm tall.

Features
• Ultra-Small 0603 Inductor (Height = 1mm)
• VIN Range: 2.2V to 5.5V
• VOUT Fixed 1.8V
• 400mA Max Output Current
• Up to 98% Efficiency
• 45μA No Load Quiescent Current
• 2.2MHz Switching Frequency
• 70μs Soft Start
• Fast Load Transient
• Over-Temperature Protection
• Current Limit Protection
• 100% Duty Cycle Low-Dropout Operation
• <1μA Shutdown Current
• 0.91 x 1.235mm WLCSP Package
• Temperature Range: -40°C to +85°C

Applications
• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Microprocessor / DSP Core / IO Power
• PDAs and Handheld Computers
• USB Devices