Texas Instruments LM2598T-12

Overview

LM2598T-12 from Texas Instruments is a monolithic 150 kHz step-down (buck) switching voltage regulator in a 7-pin TO-220 package, delivering up to 1 A output current with fixed 12 V output, ±4% output voltage tolerance over line and load, and input voltage range up to 40 V. It integrates PWM controller, power switch, and internal frequency compensation for high-efficiency DC/DC conversion in industrial power supplies.

For engineers reviewing the LM2598T-12 datasheet, LM2598T-12 pinout, LM2598T-12 application, or LM2598T-12 equivalent, key selection considerations include its fixed 12 V output, 150 kHz oscillator, thermal shutdown protection, soft-start/shutdown control, and compatibility with standard off-the-shelf inductors - all critical for reliable, low-component-count buck converter designs.

Technical Context

The LM2598T-12 implements a current-mode PWM control architecture with an integrated 150 kHz fixed-frequency oscillator, enabling predictable external component sizing and stable loop response. Its two-stage current limit and thermal shutdown provide fault protection without external circuitry.

It features dedicated pins for shutdown/soft-start (SD/SS), flag output (FLAG), and delay timing (DELAY), supporting system-level power sequencing and regulation status monitoring. The feedback path is internal for fixed-output versions, eliminating external resistor networks while maintaining ±4% output accuracy across −25°C to +125°C junction temperature.

Key Specifications

Pinout & Package

LM2598T-12 is housed in a 7-pin TO-220 package (package number NDZ0007B) with bent and 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 step-down regulator applications.

Compared with LM2596T-12 and LM2678-12DDAR, the LM2598T-12 uniquely combines TO-220 through-hole robustness, integrated regulation flag with programmable delay, and proven thermal behavior in legacy industrial designs - making it optimal where diagnostic visibility and mechanical serviceability are prioritized over raw current or footprint size.

Availability

LM2598T-12 is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and programmable logic controller (PLC) I/O modules requiring stable component supply, long-term lifecycle support, and proven field reliability.

Supply support for LM2598T-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 technologies, with decades of expertise in high-reliability power conversion ICs.

The LM2598 series was designed specifically for cost-sensitive, medium-power DC/DC applications demanding simplicity, thermal resilience, and integrated protection - targeting industrial, automotive, and instrumentation markets where long-lifecycle support and design-in confidence are essential.

FAQ

What is the maximum input voltage rating for the LM2598T-12?

The LM2598T-12 has an absolute maximum input voltage rating of 45 V, but its recommended operating input voltage range is 4.5 V to 40 V. Operation within this 40 V limit ensures compliance with electrical specifications including output regulation, efficiency, and thermal performance across temperature extremes. Exceeding 40 V may cause premature device stress or reduced lifetime, even if below the 45 V absolute maximum.

Does the LM2598T-12 require an external feedback resistor network?

No, the LM2598T-12 does not require an external feedback resistor network. As a fixed-output version, its feedback node (Pin 4) is internally connected to the 12 V output, eliminating external components and associated layout sensitivity. This simplifies design, improves accuracy, and enhances long-term stability compared to adjustable variants like LM2598-ADJ.

How does the FLAG pin on the LM2598T-12 function in practice?

The FLAG pin on the LM2598T-12 is an open-drain output that pulls low when the regulated output falls below 92–98% of nominal 12 V (i.e., 11.04–11.76 V). Its assertion is delayed by an external capacitor on the DELAY pin (typically 0.1 µF for ~10 ms), preventing false triggers during load transients. This allows direct interfacing with MCU GPIOs for real-time power health monitoring in industrial systems.

Can the LM2598T-12 operate without a heatsink under full 1 A load?

Yes - the LM2598T-12 can operate without an external heatsink at full 1 A load when ambient temperature remains below 50°C and the TO-220 tab is soldered to ≥1 in² of 1 oz. copper on the PCB. Its θ_JA = 50 °C/W and θ_JC = 2 °C/W enable sufficient passive cooling in typical industrial enclosures, as confirmed by TI's thermal models and application notes for the NDZ0007B package.

What type of catch diode is recommended for use with the LM2598T-12?

A Schottky diode rated for ≥3 A average current and ≥50 V reverse voltage is recommended for the LM2598T-12, such as the 1N5822 (3 A, 40 V). Schottky diodes minimize conduction losses and reverse recovery time, directly improving efficiency and reducing switching noise. Fast recovery diodes (≤50 ns t_rr) are acceptable alternatives, but standard PN rectifiers like 1N5400 must be avoided due to excessive switching loss and potential instability.