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
♦ 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 Amplifier Supply