Texas Instruments LM2598T-3.3

Overview

LM2598T-3.3 from Texas Instruments is a monolithic 150 kHz step-down (buck) switching regulator IC delivering a fixed 3.3 V output at up to 1 A, with ±4% output voltage tolerance over line and load, input voltage range up to 40 V, and integrated thermal shutdown and current limiting. It serves as a high-efficiency primary DC-DC converter in industrial power supplies and embedded system rails.

For engineers reviewing the LM2598T-3.3 datasheet, LM2598T-3.3 pinout, LM2598T-3.3 application, or LM2598T-3.3 equivalent, key selection considerations include its fixed 3.3 V output, TO-220-7 package thermal performance, 150 kHz oscillator frequency enabling compact magnetics, and built-in soft-start/shutdown control for reliable power sequencing.

Technical Context

The LM2598T-3.3 implements a current-mode buck topology with internal 150 kHz fixed-frequency oscillator, two-stage current limit protection, and an out-of-regulation error flag with programmable delay. Its feedback loop is internally compensated, eliminating external compensation components.

It integrates a high-side N-channel DMOS switch, internal soft-start ramp generator, and shutdown logic that reduces quiescent current to 85 μA. The device operates across −25°C to +125°C junction temperature and supports input voltages from 4.5 V to 40 V, making it suitable for unregulated 12 V or 24 V bus regulation.

Key Specifications

Pinout & Package

LM2598T-3.3 is housed in a 7-pin TO-220 package (package number NDZ0007B) with bent/staggered leads. The exposed tab is electrically connected to Pin 2 (Ground) and serves as the primary thermal path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with LM2596T-3.3, the LM2598T-3.3 adds critical supervision (FLAG/DELAY) and marginally better efficiency; versus MP1584EN-LF-Z, it trades higher-frequency miniaturization for robust fault monitoring and TO-220 thermal reliability in industrial environments.

Availability

LM2598T-3.3 is available at Aetrix Electronics and suitable for industrial power supplies, embedded system rails, and on-card switching regulators requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for LM2598T-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, embedded processing, and power management technologies, with decades of expertise in switching regulator design and manufacturing.

The LM2598 series was developed as part of TI's SIMPLE SWITCHER® portfolio to deliver rugged, easy-to-use buck regulators for industrial and embedded applications where reliability, thermal resilience, and minimal external components are essential.

FAQ

What is the maximum input voltage rating for the LM2598T-3.3?

The absolute maximum input voltage for the LM2598T-3.3 is 45 V, but the recommended operating range is 4.5 V to 40 V per the Electrical Characteristics table. Exceeding 40 V may compromise long-term reliability and is outside guaranteed specifications. The LM2598T-3.3 includes internal overvoltage clamp protection on the IN pin, but sustained operation above 40 V is not advised in production designs.

Does the LM2598T-3.3 require external feedback resistors?

No, the LM2598T-3.3 does not require external feedback resistors. As a fixed-output variant, its 3.3 V regulation is achieved via an internal resistor divider and reference, with the FB pin internally connected and not accessible externally. This eliminates layout sensitivity, resistor tolerance errors, and BOM overhead - a key differentiator from the adjustable LM2598-ADJ version.

Can the LM2598T-3.3 operate without a heatsink at 1 A load?

Yes, the LM2598T-3.3 can operate without a heatsink at 1 A load when ambient temperature remains ≤50°C and the input voltage is ≤12 V, as confirmed in the Applications section of the datasheet. Its TO-220-7 package has θ_JA = 50 °C/W (no heatsink), resulting in ~39°C junction rise at 1 A/12 V (78% efficiency), well below the +125°C max operating junction temperature.

What is the purpose of the DELAY pin on the LM2598T-3.3?

The DELAY pin on the LM2598T-3.3 sets the response time of the FLAG output using an external capacitor to ground. A 0.1 μF capacitor yields ~10 ms delay, preventing false flag assertions during brief load transients or startup undershoot. This configurable delay ensures the FLAG signal reflects true regulation failure rather than momentary disturbances - a critical feature for industrial fault logging and safe shutdown sequences.

How does the LM2598T-3.3 handle short-circuit conditions?

The LM2598T-3.3 employs two-stage current limiting: first, peak current limit (1.2–2.6 A) clamps switch conduction; second, under sustained overload, it enters hiccup mode with thermal shutdown at +150°C. After cooldown, it auto-restarts. This protects the internal DMOS switch and external diode/inductor without requiring external current-sense circuitry - a core reliability feature validated across −25°C to +125°C operation.