DESCRIPTION
The LT ®1959 is a 500kHz monolithic buck mode switching regulator functionally identical to the LT1506 but optimized for lower output voltage applications. It will operate down to 1.21V output compared to 2.42V for the LT1506. A 4.5A switch is included on the die along with all the necessary oscillator, control and logic circuitry. High switching frequency allows a considerable reduction in the size of external components. The topology is current mode for fast transient response and good loop stability.

FEATURES
■ Operates with Input as Low as 4V
■ Output Range Down to 1.21V
■ Constant 500kHz Switching Frequency
■ Uses All Surface Mount Components
■ Inductor Size Reduced to 1.8µH
■ Saturating Switch Design: 0.07Ω
■ Shutdown Current: 20µA
■ Easily Synchronizable
■ Cycle-by-Cycle Current Limiting
■ 4.5A Switch
■ Current Mode Control

APPLICATIONS
■ Portable Computers
■ Battery-Powered Systems
■ Battery Chargers
■ Distributed Power
■ 5V to 3.3V Conversion
■ 5V to 2.5V Conversion
■ 5V to 1.8V Conversion