SIMPLE SWITCHER® 40V, 500mA Low Component Count Step-Down Regulator

The LM2674 series of regulators are

monolithic integrated circuits built with a LMDMOS process. These regulators provide

all the active functions for a step-down (buck) switching regulator, capable of

driving a 500mA load current with excellent line and load regulation. These devices

are available in fixed output voltages of 3.3V, 5V, 12V, and an adjustable output

version.

Requiring a minimum number of external

components, these regulators are simple to use and include patented internal

frequency compensation and a fixed frequency oscillator.

The LM2674 series operates at a

switching frequency of 260kHz, thus allowing smaller sized filter components than

what is required with lower frequency switching regulators. Because of very high

efficiency (> 90%), the copper traces on the printed-circuit board are the only

heat sinking required.

A family of standard inductors for use

with the LM2674 are available from several different manufacturers. This feature

greatly simplifies the design of switch-mode power supplies using these advanced

ICs. Also included in the data sheet are selector guides for diodes and capacitors

designed to work in switch-mode power supplies.

Other features include a specified

±1.5% tolerance on output voltage within specified input voltages and output load

conditions, and ±10% on the oscillator frequency. External shutdown is included,

featuring typically 50µA standby current. The output switch includes current

limiting, as well as thermal shutdown for full protection under fault

conditions.