Texas Instruments LM2678T-5.0/NOPB

Overview

LM2678T-5.0/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 5 A output current with fixed 5 V output, 8–40 V input range, 260 kHz fixed-frequency operation, and ±2% output voltage tolerance over full line/load/temperature. It integrates a 120 mΩ DMOS high-side switch and supports efficient system preregulation in industrial power supplies.

For engineers reviewing the LM2678T-5.0/NOPB datasheet, LM2678T-5.0/NOPB pinout, LM2678T-5.0/NOPB application, or LM2678T-5.0/NOPB equivalent, key selection criteria include its 5 A continuous load capability, 50 µA shutdown quiescent current, thermal shutdown protection, ON/OFF control interface, and compatibility with standard off-the-shelf inductors and Schottky diodes per TI's SIMPLE SWITCHER design methodology.

Technical Context

The LM2678T-5.0/NOPB implements a fixed-frequency pulse-width modulation (PWM) controller with internal 260 kHz oscillator and integrated 120 mΩ DMOS high-side power switch. Its feedback loop uses an internal resistive divider for 5 V regulation, eliminating external resistor networks required by adjustable versions.

It operates in continuous conduction mode (CCM) across 100 mA–5 A loads, features built-in current limiting (6.1–8.3 A), thermal shutdown, and ON/OFF logic-level enable with 1.4 V threshold. The device maintains ±2% output accuracy from –40°C to +125°C junction temperature and supports input transients up to 45 V absolute maximum.

Key Specifications

Pinout & Package

LM2678T-5.0/NOPB is supplied in the KTW (TO-263-7) thermally enhanced surface-mount package (10.1 mm × 15.24 mm), featuring exposed DAP connected to GND for optimal thermal dissipation. Pin 1 is Switch_output, Pin 2 is Input, Pin 3 is CB (bootstrap capacitor connection), Pin 4 is GND, Pin 5 is NC, Pin 6 is FB (internally tied for fixed 5 V version), and Pin 7 is ON/OFF enable.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2678T-5.0/NOPB, LM2596T-5.0/NOPB offers lower cost but sacrifices 40% current capacity and control flexibility, while TPS54560BQPWPRQ1 adds automotive qualification and programmability at higher complexity and BOM cost-making LM2678T-5.0/NOPB optimal for industrial 5 A fixed-output applications needing simplicity, thermal margin, and proven field reliability.

Availability

LM2678T-5.0/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive infotainment pre-regulators, and telecom remote radio units requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM2678T-5.0/NOPB 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 LM2678 series belongs to TI's SIMPLE SWITCHER® family-designed specifically for rapid, robust, and low-risk implementation of high-current DC-DC buck converters using minimal external components and industry-standard passives.

FAQ

What is the maximum input voltage rating for LM2678T-5.0/NOPB?

The absolute maximum input voltage for LM2678T-5.0/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Exceeding 40 V during normal operation risks violating the device's safe operating area, especially under high ambient temperatures or heavy load conditions. TI specifies 40 V as the upper limit for reliable continuous operation with proper thermal management.

Does LM2678T-5.0/NOPB require external feedback resistors?

No, LM2678T-5.0/NOPB does not require external feedback resistors. As a fixed 5 V output variant, it incorporates an internal precision resistive divider connected to the FB pin, enabling direct connection of FB to the output capacitor. This eliminates tuning components, reduces layout sensitivity, and ensures factory-trimmed ±2% output accuracy without user calibration.

How does the ON/OFF pin function on LM2678T-5.0/NOPB?

The ON/OFF pin (Pin 7) of LM2678T-5.0/NOPB is a logic-compatible enable input: applying ≥1.4 V (typical) turns the regulator on, while ≤0.8 V places it in shutdown mode with only 50 µA quiescent current. An internal 20 µA pull-up allows the pin to be left floating for default-on operation. No external pull-up resistor is required unless driving from open-drain logic.

What thermal performance can be expected from LM2678T-5.0/NOPB in the KTW package?

In the KTW (TO-263-7) package with adequate PCB copper area (≥0.4896 in² of 1 oz. copper), LM2678T-5.0/NOPB achieves a junction-to-ambient thermal resistance (R_θJA) of 35°C/W. At 5 A output and 12 V input, typical power dissipation is ~1.2 W, resulting in ~42°C junction rise above ambient-well within the –40°C to +125°C operating range when mounted on standard FR4 with thermal vias to inner layers.

Is LM2678T-5.0/NOPB RoHS compliant and lead-free?

Yes, LM2678T-5.0/NOPB is RoHS compliant and lead-free. The "/NOPB" suffix explicitly denotes lead-free packaging per JEDEC J-STD-020 standards. TI certifies this variant as fully compliant with EU RoHS Directive 2011/65/EU and meets IPC/JEDEC J-STD-020 moisture sensitivity level (MSL) 3 requirements for surface-mount assembly.