4.5A, 500kHz Step-Down Switching Regulator

The LT1374 is a 500kHz monolithic buck mode switching regulator. 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. Both fixed output voltage and adjustable parts are available.

A special high speed bipolar process and new design techniques achieve high efficiency at high switching frequency. Efficiency is maintained over a wide output current range by using the output to bias the circuitry and by utilizing a supply boost capacitor to saturate the power switch.

The LT1374 is available in standard 7-pin DD, TO-220, fused lead SO-8 and 16-pin exposed pad TSSOP packages. Full cycle-by-cycle short-circuit protection and thermal shutdown are provided. Standard surface mount external parts may be used, including the inductor and capacitors. There is the optional function of shutdown or synchronization. A shutdown signal reduces supply current to 20µA. Synchronization allows an external logic level signal to increase the internal oscillator from 580kHz to 1MHz.

Applications

* Portable Computers

* Battery-Powered Systems

* Battery Chargers

* Distributed Power

* Constant 500kHz Switching Frequency

* High Power 16-Pin TSSOP Package Available

* Uses All Surface Mount Components

* Inductor Size Reduced to 1.8µH

* Saturating Switch Design: 0.07Ω

* Effective Supply Current: 2.5mA

* Shutdown Current: 20µA

* Cycle-by-Cycle Current Limiting

* Easily Synchronizable