LM2576/LM2576HV Series

SIMPLE SWITCHER^® 3A Step-Down Voltage Regulator

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

• 3.3V, 5V, 12V, 15V, and adjustable output versions
• Adjustable version output voltage range, 1.23V to 37V (57V for HV version) ±4% max over line and load conditions
• Guaranteed 3A output current
• Wide input voltage range, 40V up to 60V for HV version n 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
• P+ Product Enhancement tested

Applications

• Simple high-efficiency step-down (buck) regulator
• Efficient pre-regulator for linear regulators
• On-card switching regulators
• Positive to negative converter (Buck-Boost)

Typical Application (Fixed Output Voltage Versions)

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Maximum Supply Voltage

LM2576 45V

LM2576HV 63V

ON /OFF Pin Input Voltage −0.3V ≤ V ≤ +V_IN

Output Voltage to Ground (Steady State) −1V

Power Dissipation Internally Limited

Storage Temperature Range −65˚C to +150˚C

Maximum Junction Temperature 150˚C

Minimum ESD Rating (C = 100 pF, R = 1.5 kΩ) 2 kV

Lead Temperature (Soldering, 10 Seconds) 260˚C

Operating Ratings

Temperature Range

LM2576/LM2576HV −40˚C ≤ TJ ≤ +125˚C

Supply Voltage

LM2576 40V

LM2576HV 60V

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Block Diagram

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