General Description
The MAX1920/MAX1921 step-down converters deliver over 400mA to outputs as low as 1.25V. These converters use a unique proprietary current-limited control scheme that achieves over 90% efficiency. These devices maintain extremely low quiescent supply current (50μA), and their high 1.2MHz (max) operating frequency permits small, low-cost external components. This combination makes the MAX1920/MAX1921 excellent high-efficiency alternatives to linear regulators in space-constrained applications.
Internal synchronous rectification greatly improves efficiency and eliminates the external Schottky diode required in conventional step-down converters. Both devices also include internal digital soft-start to limit input current upon startup and reduce input capacitor requirements.

Features
● 400mA Guaranteed Output Current
● Internal Synchronous Rectifier for > 90% Efficiency
● Tiny 6-Pin SOT23 Package
● Available in 6-Pin TDFN Package (MAX1920)
● Up to 1.2MHz Switching Frequency for Small
   External Components
● 50μA Quiescent Supply Current
● 0.1μA Logic-Controlled Shutdown
● 2V to 5.5V Input Range
● Fixed 1.5V, 1.8V, 2.5V, 3V, and 3.3V Output
   Voltages (MAX1921)
● Adjustable Output Voltage (MAX1920)
● ±1.5% Initial Accuracy
● Soft-Start Limits Startup Current

Applications
● Next-Generation Wireless Handsets
● PDAs, Palmtops, and Handy-Terminals
● Battery-Powered Equipment
● CDMA Power Amplifer Supply