Texas Instruments LM2676T-ADJ/NOPB

Overview

LM2676T-ADJ/NOPB from Texas Instruments is a monolithic step-down (buck) DC/DC switching regulator delivering up to 3A output current with adjustable output voltage (1.2V to 37V), 260kHz fixed-frequency operation, ±2% output voltage tolerance over line/load/temperature, and 8V–40V input range. It integrates a 150mΩ DMOS high-side switch and supports ON/OFF control for low-power standby mode.

For engineers reviewing the LM2676T-ADJ/NOPB datasheet, LM2676T-ADJ/NOPB pinout, LM2676T-ADJ/NOPB application, or LM2676T-ADJ/NOPB equivalent, key selection criteria include its adjustable feedback architecture, thermal shutdown and current limiting, TO-263-7 (KTW) package thermal performance, and compatibility with standard off-the-shelf inductors and Schottky diodes in industrial power supply designs.

Technical Context

The LM2676T-ADJ/NOPB implements a voltage-mode PWM controller with a fixed 260kHz oscillator and internal high-side DMOS FET. Its feedback loop senses output voltage via an external resistor divider connected to the FB pin, enabling precise regulation across 1.2V–37V. The device operates in continuous conduction mode at full load and includes built-in thermal shutdown, cycle-by-cycle current limiting, and soft-start functionality.

Control logic responds to the ON/OFF pin: <0.8V forces shutdown with 50µA standby current; >1.4V enables regulation. The CB pin supplies bootstrapped gate drive to the high-side switch, requiring a 100nF capacitor to VSW. Switch node (pin 1) transitions between VIN and ~−0.5V (Schottky drop) during operation.

Key Specifications

Pinout & Package

LM2676T-ADJ/NOPB is supplied in the KTW (TO-263-7) thermally enhanced surface-mount package, featuring a 10.1mm × 15.24mm outline and exposed thermal pad soldered to PCB ground plane for optimal heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2596T-ADJ/NOPB, LM2676T-ADJ/NOPB delivers higher efficiency and tighter output tolerance at 260kHz, while LMR51430RGER offers superior integration and footprint reduction but requires redesign for synchronous operation and layout.

Availability

LM2676T-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, motor drive control circuits, electricity metering systems, and communication module power management requiring stable component supply and long-term manufacturability.

Supply support for LM2676T-ADJ/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 LM2676 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for robust, easy-to-implement DC/DC buck regulators targeting industrial, metering, and communications equipment where reliability, thermal performance, and design simplicity are critical.

FAQ

What is the maximum output voltage that can be set using LM2676T-ADJ/NOPB?

The LM2676T-ADJ/NOPB supports an adjustable output voltage range from 1.2V to 37V, determined by the external resistor divider connected to the FB pin. This is based on the internal 1.21V reference voltage (V_FB = 1.21V ±1.2%) and the equation V_OUT = V_FB × (1 + R1/R2). Operation beyond 37V is not guaranteed per datasheet specifications.

Does LM2676T-ADJ/NOPB require an external Schottky diode, and why?

Yes, LM2676T-ADJ/NOPB requires an external Schottky diode connected from the SW pin to GND. Because it is an asynchronous buck controller, the internal DMOS switch only provides the high-side path; the diode completes the current path during the switch OFF period. A low-forward-voltage Schottky diode minimizes conduction loss and preserves efficiency - typical selections include 3A-rated devices with <0.5V V_F.

What thermal performance can be expected from LM2676T-ADJ/NOPB in the KTW package?

In the KTW (TO-263-7) package, LM2676T-ADJ/NOPB achieves a junction-to-ambient thermal resistance (R_θJA) of 56°C/W with minimal copper (0.136 in²) and 26°C/W with enhanced copper (1.0064 in² plus 12 vias). These values assume proper soldering of the exposed thermal pad to a solid ground plane - critical for sustaining 3A continuous output at elevated ambient temperatures.

How does the ON/OFF pin function on LM2676T-ADJ/NOPB, and what voltage levels enable/disable it?

The ON/OFF pin on LM2676T-ADJ/NOPB is a logic-compatible enable input: applying ≥1.4V (typically pulled high or driven by MCU GPIO) activates regulation; applying ≤0.8V (or grounding) places the device in shutdown mode with 50µA quiescent current. An internal 20µA pull-up allows open-circuit operation for default-enable configurations, and a 7V Zener clamp protects against overvoltage.

Can LM2676T-ADJ/NOPB operate with input voltages below 8V?

No - the absolute minimum recommended input voltage for LM2676T-ADJ/NOPB is 8V, as specified in Section 5.3 Recommended Operating Conditions. Operation below 8V may result in failure to start, unstable regulation, or violation of internal bias requirements. The 8V–40V range ensures reliable startup, PWM control stability, and sufficient headroom for the internal DMOS gate drive circuitry.