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