1 Features

1• 3.3-V, 5-V, 12-V, 15-V, and Adjustable Output

Versions

• Adjustable Version Output Voltage Range,1.23 V

to 37 V (57 V for HV Version) ±4% Maximum Over

Line and Load Conditions

• Specified 3-A Output Current

• Wide Input Voltage Range: 40 V Up to 60 V for

HV Version

• Requires Only 4 External Components

• 52-kHz Fixed-Frequency Internal Oscillator

• TTL-Shutdown Capability, Low-Power Standby

Mode

• High Efficiency

• Uses Readily Available Standard Inductors

• Thermal Shutdown and Current Limit Protection

2 Applications

• Simple High-Efficiency Step-Down (Buck)

Regulator

• Efficient Preregulator for Linear Regulators

• On-Card Switching Regulators

• Positive-to-Negative Converter (Buck-Boost)

3 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 3-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 fault protection 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 ±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.