The LM2574xx series of regulators are monolithic integrated circuits that provide all the
active functions for a step-down (buck) switching regulator, capable of driving a 0.5-A load with
excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V,
5 V, 12 V, 15 V, and an adjustable output version.
Requiring a minimum number of external components, these regulators are simple to use and
include internal frequency compensation and a fixed-frequency oscillator.
The LM2574xx series offers a high-efficiency replacement for popular three-terminal
linear regulators. Because of its high efficiency, the copper traces on the printed-circuit board
(PCB) are normally the only heat sinking needed.
A standard series of inductors optimized for use with the LM2574 are available from
several different manufacturers. This feature greatly simplifies the design of switch-mode power
Other features include a specified ±4% tolerance on output voltage within specified input
voltages and output load conditions, and ±10% on the oscillator frequency. External shutdown is
included, featuring 50-µA (typical) standby current. The output switch includes cycle-by-cycle
current limiting, as well as thermal shutdown for full protection under fault conditions.
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