Texas Instruments LM2594M-3.3

Overview

LM2594M-3.3 from Texas Instruments is a monolithic nonsynchronous step-down (buck) DC-DC converter delivering 3.3 V at up to 0.5 A, with 150-kHz fixed-frequency operation, ±4% output voltage tolerance over line and load, and input voltage support up to 40 V. It serves as a compact, low-component-count power supply for embedded microcontroller rails in industrial control modules.

For engineers reviewing the LM2594M-3.3 datasheet, LM2594M-3.3 pinout, LM2594M-3.3 application, or LM2594M-3.3 equivalent, key selection factors include its 0.5-A guaranteed output current, 85-μA standby quiescent current, thermal shutdown protection, SOIC-8 package compatibility, and fixed 3.3-V output eliminating external feedback resistors.

Technical Context

The LM2594M-3.3 integrates a PWM controller, power switch, oscillator, and internal frequency compensation in a single SOIC-8 package. Its architecture uses a fixed 150-kHz switching frequency with discontinuous or continuous conduction mode operation depending on load and inductor selection.

It features TTL-compatible ON/OFF control with 1.3-V threshold, internal current limiting (0.65–1.3 A peak), and thermal shutdown. Output regulation relies on internal reference and feedback sensing via dedicated pin - though unused in fixed-output variants, it remains accessible for monitoring or modification.

Key Specifications

Pinout & Package

LM2594M-3.3 is supplied in an 8-pin surface-mount SOIC package (D package), body size 4.90 mm × 3.91 mm, with exposed pad not present and no thermal pad requirement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2594M-3.3, LM2594HVM-3.3 extends input range without layout change, while LMR36506RNXR delivers superior efficiency and integration at the cost of redesign effort and non-interchangeable packaging.

Availability

LM2594M-3.3 is available at Aetrix Electronics and suitable for industrial control, sensor node power, and legacy equipment retrofit requiring stable component supply, long-term lifecycle assurance, and SOIC-8 compatibility.

Supply support for LM2594M-3.3 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 and embedded processing technologies, with decades of expertise in power management ICs.

The LM2594xx series was designed as a rugged, easy-to-use SIMPLE SWITCHER® solution for cost-sensitive, medium-power DC-DC conversion in industrial, automotive, and telecom infrastructure where reliability and minimal external components are critical.

FAQ

What is the maximum input voltage rating for the LM2594M-3.3?

The LM2594M-3.3 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, though brief transients up to 45 V are tolerated per absolute maximum ratings. For designs requiring >40 V input, the LM2594HVM-3.3 variant supports up to 60 V and shares identical pinout and functionality.

Does the LM2594M-3.3 require external feedback resistors to set output voltage?

No, the LM2594M-3.3 is a fixed-output variant with internal feedback network trimmed to 3.3 V. Pin 4 (Feedback) is internally connected to the reference and does not require external resistors. It remains accessible for optional monitoring or precision trimming but is not necessary for standard operation of the LM2594M-3.3.

Can the LM2594M-3.3 be used in discontinuous conduction mode (DCM)?

Yes, the LM2594M-3.3 supports both continuous and discontinuous conduction modes depending on inductor value and load. At light loads (<200 mA) or with smaller inductors (e.g., 47 μH), it naturally operates in DCM - characterized by zero inductor current periods and benign damped ringing on the switch node, which does not indicate instability and requires no compensation changes.

What thermal performance can be expected from the LM2594M-3.3 in SOIC-8 package?

In the SOIC-8 (D) package, the LM2594M-3.3 has a junction-to-ambient thermal resistance (RθJA) of 150°C/W on a standard 4-layer JEDEC board. At 0.5-A load and 12-V input, typical power dissipation is ~1.2 W, resulting in ~180°C junction rise above ambient - necessitating proper copper pour, airflow, or derating. For sustained 0.5-A operation, keep ambient ≤60°C or add thermal relief.

Is the LM2594M-3.3 RoHS compliant and lead-free?

Yes, the LM2594M-3.3 is RoHS compliant and lead-free per Texas Instruments' current manufacturing standards. The SOIC-8 package uses matte tin lead finish, and the device meets JEDEC J-STD-020 moisture sensitivity level (MSL) 3. Full compliance documentation, including material declarations and test reports, is available via TI's product folder for LM2594M-3.3.