Texas Instruments LM2576SX-12

Overview

LM2576SX-12 from Texas Instruments is a monolithic 3-A non-synchronous step-down (buck) DC-DC regulator in TO-220-5 (KC) package, delivering fixed 12 V output with ±4% tolerance over line and load, 40 V max input voltage, and 52 kHz fixed-frequency operation. It serves as a high-efficiency replacement for linear regulators in industrial power supplies, motor drives, and test equipment.

For engineers reviewing the LM2576SX-12 datasheet, LM2576SX-12 pinout, LM2576SX-12 application, or LM2576SX-12 equivalent, key selection considerations include its 3-A continuous output capability, TTL-compatible ON/OFF control with 50 µA standby current, cycle-by-cycle current limiting, thermal shutdown protection, and compatibility with standard off-the-shelf inductors.

Technical Context

The LM2576SX-12 integrates a 3-A NPN power switch, 52-kHz oscillator, error amplifier, current-limit comparator, and thermal shutdown circuit in a single monolithic IC. Its fixed 12 V output eliminates external feedback resistors, simplifying design while maintaining ±4% regulation across −40°C to +125°C junction temperature.

It operates in continuous conduction mode under full load and transitions to discontinuous mode at light loads. The internal switch features 1.8 V typical saturation voltage at 3 A, enabling high efficiency (up to 88% at 15 V_IN/3 A) without requiring synchronous rectification or external gate drivers.

Key Specifications

Pinout & Package

LM2576SX-12 uses the KC (TO-220-5) package with 10.16 mm × 8.51 mm body size and integral heat slug connected to GND. The tab must be thermally coupled to a heatsink or large copper pour for reliable 3-A operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Compared with LM2576SX-12, LM2576T-12 offers identical performance in through-hole form, while LM2576HV-12 extends input range to 60 V without altering output behavior or footprint - both preserve design reuse but address distinct mechanical or voltage-range constraints.

Availability

LM2576SX-12 is available at Aetrix Electronics and suitable for industrial motor drives, network equipment power supplies, test and measurement instruments, and home appliance control boards requiring stable component supply and long-term manufacturability.

Supply support for LM2576SX-12 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-reliability power conversion solutions.

The LM2576 series was designed as a SIMPLE SWITCHER® solution to replace linear regulators in cost-sensitive, medium-power applications - emphasizing ease of use, minimal external components, and robust fault protection.

FAQ

What is the maximum input voltage rating for LM2576SX-12?

The LM2576SX-12 has an absolute maximum input voltage of 45 V and a recommended maximum operating input voltage of 40 V. Exceeding 40 V risks reduced reliability and lifetime, especially at elevated temperatures. For designs requiring >40 V input, the LM2576HV-12 variant - rated for 60 V - is the appropriate alternative. Always observe derating guidelines in the TI datasheet SNVS107G.

Does LM2576SX-12 require external feedback resistors?

No, the LM2576SX-12 does not require external feedback resistors. As a fixed-output version, its internal feedback divider is factory-trimmed to deliver 12 V with ±4% accuracy. Pin 4 (FEEDBACK) is internally connected to the output and must remain unconnected in PCB layout - unlike the adjustable LM2576ADJ, which requires external R1/R2.

How is thermal management handled for LM2576SX-12 at full 3-A load?

At 3-A continuous load, LM2576SX-12 dissipates approximately 5.4 W (based on 1.8 V saturation voltage). With its TO-220-5 (KC) package, thermal resistance to ambient is 32.4°C/W. To maintain T_J ≤125°C at 25°C ambient, ≥120 cm² of 2-oz copper connected to the tab is recommended. Use of a mechanical heatsink reduces required copper area significantly.

Can LM2576SX-12 be synchronized to an external clock?

No, LM2576SX-12 cannot be synchronized to an external clock. It uses an internal fixed-frequency 52-kHz oscillator with ±10% tolerance. There is no SYNC or CLKIN pin, and frequency adjustment is not supported. For synchronizable buck regulators, consider newer TI parts like the LM76003 or LMR51430.

What protection features are integrated into LM2576SX-12?

LM2576SX-12 integrates cycle-by-cycle current limiting, thermal shutdown (triggered at ~150°C junction temperature), and undervoltage lockout (UVLO) that disables operation below ~3.5 V input. It also features a TTL-compatible ON/OFF pin for remote enable/disable with 50 µA standby current. No external protection circuitry is required for basic fault coverage.