Texas Instruments LM2576T-12

Overview

LM2576T-12 from Texas Instruments is a monolithic 3-A non-synchronous step-down (buck) DC-DC voltage regulator in TO-220 package, delivering fixed 12 V output with ±4% tolerance over line and load, 40 V max input, and 52 kHz fixed-frequency operation. It replaces linear regulators in high-current power supplies for motor drives, test equipment, and industrial appliances.

For engineers reviewing the LM2576T-12 datasheet, LM2576T-12 pinout, LM2576T-12 application, or LM2576T-12 equivalent, key selection considerations include its 3-A continuous output capability, thermal shutdown and cycle-by-cycle current limiting, TTL-compatible ON/OFF control, and minimal external component count (only four required).

Technical Context

The LM2576T-12 integrates a 3-A NPN power switch, 1.23-V bandgap reference, error amplifier, 52-kHz oscillator, and thermal shutdown circuitry into a single TO-220-5 package. Its fixed 12-V output eliminates external feedback resistors, simplifying design while maintaining ±4% regulation across −40°C to +125°C junction temperature.

Operation relies on pulse-width modulation with cycle-by-cycle current limiting and automatic frequency reduction (to ~11 kHz) during overload or short-circuit conditions. The ON/OFF pin enables TTL-level shutdown with 50-μA standby current, and the internal switch exhibits 1.4–2.0 V saturation voltage at 3 A.

Key Specifications

Pinout & Package

LM2576T-12 uses the KC (TO-220-5) package with 10.16 mm × 8.51 mm body size and integral heat-tab electrically connected to GROUND. Thermal resistance is R_θJA = 32.4°C/W on standard PCB, reduced further with heatsink attachment to the tab.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576HVT-12, the LM2576T-12 trades input voltage headroom for cost and thermal simplicity; compared with LMR51430RNXR, it offers proven ruggedness and minimal external components at the expense of efficiency and frequency flexibility.

Availability

LM2576T-12 is available at Aetrix Electronics and suitable for industrial motor drives, test and measurement equipment, home appliance control boards, and server fan controllers requiring stable component supply and long-term manufacturability.

Supply support for LM2576T-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 designing analog ICs, embedded processors, and power management solutions for industrial, automotive, and consumer applications.

The LM2576 series was developed as part of TI's SIMPLE SWITCHER® portfolio to provide robust, easy-to-use buck regulators that replace linear regulators with minimal design effort and external components.

FAQ

What is the maximum input voltage rating for the LM2576T-12?

The LM2576T-12 has an absolute maximum input voltage of 45 V and a recommended maximum operating input voltage of 40 V. Exceeding 40 V risks violating recommended operating conditions and may trigger thermal shutdown or reduce reliability. For 48-V systems, the LM2576HVT-12 (60-V rated) is the appropriate alternative. Always refer to Section 6.1 and 6.3 of the LM2576 datasheet for derating guidance.

Does the LM2576T-12 require external feedback resistors to set the output voltage?

No. The LM2576T-12 is a fixed-output variant with the 12-V feedback divider integrated internally. Pin 4 (FEEDBACK) is internally connected to the output and requires no external components. This distinguishes it from the LM2576-ADJ version, which uses external resistors to program output voltage between 1.23 V and 37 V. The fixed architecture simplifies layout and improves regulation stability.

How does the ON/OFF pin function on the LM2576T-12?

The ON/OFF pin (Pin 5) provides TTL-compatible enable control: pulling it below 1.2 V (typically to GND) enables regulation, while raising it above 1.4 V disables the output and reduces quiescent current to 50 μA typical. The pin must never be left floating. This feature allows precise power sequencing in multi-rail systems and low-power standby modes without external logic-level translators.

What thermal management is required for the LM2576T-12 at full 3-A load?

At 3-A output with 15-V input and 12-V output, the LM2576T-12 dissipates approximately 9 W. With R_θJA = 32.4°C/W in TO-220 package, junction temperature rise is ~290°C above ambient - exceeding safe limits. Therefore, a heatsink attached to the grounded tab is mandatory. A 10°C/W heatsink reduces rise to ~100°C, keeping T_J within 125°C limit at 25°C ambient. PCB copper area also significantly improves thermal performance.

Can the LM2576T-12 be used in synchronous rectification configurations?

No. The LM2576T-12 is a non-synchronous buck regulator with an internal NPN switch and requires an external catch diode (e.g., 1N5822). It does not support synchronous rectification because it lacks a second, complementary MOSFET driver or timing control for low-side FET gating. For synchronous operation, consider TI's LMR51430 or LM76003 families, which integrate both high- and low-side MOSFETs and drivers.