General Description

The LM2576 series of regulators are monolithic integrated

circuits that provide all the active functions for a step-down

(buck) switching regulator, capable of driving 3A load with

excellent line and load regulation. These devices are available

in fixed output voltages of 3.3V, 5V, 12V, 15V, 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 LM2576 series offers a high-efficiency replacement for

popular three-terminal linear regulators. It substantially reduces

the size of the heat sink, and in some cases no heat

sink is required.

A standard series of inductors optimized for use with the

LM2576 are available from several different manufacturers.

This feature greatly simplifies the design of switch-mode

power supplies.

Other features include a guaranteed ±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.

Features

n 3.3V, 5V, 12V, 15V, and adjustable output versions

n Adjustable version output voltage range,

1.23V to 37V (57V for HV version) ±4% max over

line and load conditions

n Guaranteed 3A output current

n Wide input voltage range, 40V up to 60V for

HV version

n Requires only 4 external components

n 52 kHz fixed frequency internal oscillator

n TTL shutdown capability, low power standby mode

n High efficiency

n Uses readily available standard inductors

n Thermal shutdown and current limit protection

n P+ Product Enhancement tested

Applications

n Simple high-efficiency step-down (buck) regulator

n Efficient pre-regulator for linear regulators

n On-card switching regulators

n Positive to negative converter (Buck-Boost)