LT1959 Datasheet | Linear Technology

LT1959 4.5A, 500k Hz Step-Down Switching Regulator Features s s s s s s s s s s s DESCRIPTIO Operates with Input as Low as 4V Output Range Down to 1.21V Constant 500k Hz Switching Frequency Uses All Surface Mount ponents 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 The LT ®1959 is a 500k Hz 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 pared 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 ponents. The topology is current mode for fast transient response and good loop stability. 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 keeping quiescent supply current to 4m A and by utilizing a supply boost capacitor to saturate the power switch. The LT1959 fits into standard 7-pin DD and fused lead SO-8 packages. Full cycle-by-cycle short-circuit protection and thermal shutdown are provided. Standard surface mount external parts are 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 580k Hz to 1MHz. , LTC and LT are registered trademarks of Linear Technology Corporation. U APPLICATIO S s s s s s s s Portable puters Battery-Powered Systems Battery Chargers Distributed Power 5V to 3.3V Conversion 5V to 2.5V Conversion 5V to 1.8V Conversion TYPICAL APPLICATION 5V to 1.8V Down Converter D2 1N914 C2 0.68µF INPUT 5V BOOST VIN VSW...