Texas Instruments LM2574MX-5.0

Overview

LM2574MX-5.0 from Texas Instruments (formerly National Semiconductor) is a monolithic 0.5A step-down (buck) switching voltage regulator with fixed 5.0V output, 52 kHz internal oscillator, 40V maximum input voltage, and integrated cycle-by-cycle current limiting and thermal shutdown. It replaces linear regulators in board-level DC-DC conversion for industrial power rails.

For engineers reviewing the LM2574MX-5.0 datasheet, LM2574MX-5.0 pinout, LM2574MX-5.0 application, or LM2574MX-5.0 equivalent, key selection criteria include guaranteed 0.5A output current, ±4% output voltage tolerance over line/load/temperature, 77% typical efficiency at 12V_IN/0.5A, TTL-compatible shutdown control, and compatibility with standard off-the-shelf 330 µH inductors.

Technical Context

The LM2574MX-5.0 implements a fixed-frequency, current-mode buck topology with an internal NPN switch, feedback comparator, oscillator, and protection circuitry. Its 52 kHz switching frequency balances EMI control and external component size, while the built-in current limit (1.0 A peak) and thermal shutdown ensure fault robustness without external sensing.

It operates in continuous conduction mode under typical loads (e.g., 0.1–0.5A at 5V), requiring only four external components: input capacitor, output capacitor, catch diode, and inductor. The feedback loop uses a precision 1.23V reference internally tied to the output for fixed versions-no external resistors needed for the LM2574MX-5.0.

Key Specifications

Pinout & Package

LM2574MX-5.0 is supplied in a 14-pin wide-body surface-mount (WM) package (NS package code M14B), thermally enhanced for PCB heat transfer via exposed pad or large copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2575T-5.0, the LM2574MX-5.0 offers lower profile and surface-mount compatibility but reduced current capacity; compared with MP1584EN-LF-Z, it trades higher integration and ease of use for lower switching frequency and simpler external component requirements.

Availability

LM2574MX-5.0 is available at Aetrix Electronics and suitable for industrial automation, embedded microcontroller power, and test equipment requiring stable component supply with long lifecycle support.

Supply support for LM2574MX-5.0 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 acquired National Semiconductor in 2011 and maintains full technical support and manufacturing continuity for the SIMPLE SWITCHER™ product line.

The LM2574MX-5.0 belongs to TI's SIMPLE SWITCHER™ family of integrated buck regulators, designed specifically for ease-of-use in cost-sensitive, medium-power DC-DC conversion where minimal external components and proven reliability are prioritized over ultra-high density or ultra-low quiescent current.

FAQ

What is the maximum input voltage rating for the LM2574MX-5.0?

The LM2574MX-5.0 has an absolute maximum input voltage of 45V and a recommended maximum operating input voltage of 40V. Exceeding 40V risks violating the device's safe operating area, especially under high ambient temperatures or heavy load. The LM2574HV variant supports up to 60V input, but the LM2574MX-5.0 is part of the standard-voltage LM2574 series and must not be operated above 40V in continuous service.

Does the LM2574MX-5.0 require external feedback resistors to set its output voltage?

No. The LM2574MX-5.0 is a fixed-output version with internal feedback network trimmed to 5.0V. Pin 5 (FEEDBACK) is internally connected to the regulated output, so no external resistors are needed - unlike the adjustable LM2574-ADJ variant. This simplifies layout, improves long-term accuracy, and eliminates resistor tolerance and drift effects on the LM2574MX-5.0 output.

Can the LM2574MX-5.0 be used in discontinuous conduction mode (DCM)?

Yes. The LM2574MX-5.0 operates naturally in discontinuous conduction mode at light loads (e.g., <50 mA), as confirmed by its datasheet waveforms and design guidelines. Its current-mode control and fixed-frequency oscillator maintain regulation across both continuous and discontinuous modes without instability or audible noise. DCM operation reduces light-load current consumption and is fully supported in typical applications.

What is the recommended inductor value for the LM2574MX-5.0 at 0.5A output?

For 5V output at 0.5A with typical 12V input, the LM2574MX-5.0 datasheet specifies a 330 µH inductor (e.g., Pulse PE-52627 or Renco RL-1284-330). This value ensures continuous conduction mode, manageable peak currents (<1.0A), and acceptable output ripple. Inductor saturation current must exceed 1.5×I_OUT (≥0.75A), and DC resistance should be minimized to preserve efficiency.

Is thermal derating required for the LM2574MX-5.0 in a 14-pin WM package?

Yes. The LM2574MX-5.0's 14-pin wide-body (M14B) package has a junction-to-ambient thermal resistance (θ_JA) of 102°C/W with minimal copper and 78°C/W with 4 in² of 1 oz. copper. At 0.5A output and 12V input, power dissipation is ~3.5W - requiring ≥2 in² of thermal copper or forced airflow to maintain T_J < 125°C. Derating curves in the datasheet show output current must be reduced above 85°C ambient unless additional copper or airflow is provided.