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 500-mA load current with excellent line and load regulation. These
devices are available in fixed output voltages of 3.3 V, 5 V, 12 V, and an adjustable output
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 260 kHz, thus allowing smaller
sized filter components than what is required with lower frequency switching regulators. Because of
its 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 an ensured ±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 50-µA
standby current. The output switch includes current limiting, as well as thermal shutdown for full protection under