Texas Instruments LM2676S-12

Overview

LM2676S-12 from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 3A output current with fixed 12V output, 260kHz fixed-frequency operation, ±2% output voltage tolerance over full line/load/temperature, and 94% peak efficiency at 24V_IN/3A. It integrates a 150mΩ DMOS high-side switch and supports ON/OFF control for low-power standby mode.

For engineers reviewing the LM2676S-12 datasheet, LM2676S-12 pinout, LM2676S-12 application, or LM2676S-12 equivalent, key selection criteria include input voltage range (8–40V), thermal performance in TO-263 package, feedback configuration for fixed-output use, and compatibility with standard off-the-shelf inductors and Schottky diodes in buck topology designs.

Technical Context

The LM2676S-12 implements a voltage-mode PWM controller with internal 260kHz oscillator and integrated 150mΩ DMOS high-side power switch. Its fixed 12V output eliminates external feedback resistors, simplifying layout and reducing component count in point-of-load applications.

It features built-in thermal shutdown, cycle-by-cycle current limiting (3.6–5.4A), and an ON/OFF pin enabling shutdown with only 50µA standby current. The device operates across –40°C to +125°C junction temperature and requires boot capacitor (CB) connection between pin 3 and switch node for gate drive boosting.

Key Specifications

Pinout & Package

LM2676S-12 is packaged in KTW (TO-263-7), a thermally enhanced surface-mount variant of TO-220 with exposed thermal pad. Dimensions: 10.1mm × 15.24mm. Mounting requires soldering the tab (DAP) to a PCB copper pour for optimal thermal performance (R_θJA = 35°C/W with 0.4896 in² copper).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2676S-12, LM2675S-12 offers identical functionality at lower current, while LMR51430RGER provides modern synchronous architecture and wider input range but demands redesign of magnetics and loop compensation - neither is pin-compatible, and both require layout revision.

Availability

LM2676S-12 is available at Aetrix Electronics and suitable for industrial power conversion, smart metering, and motor control applications requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.

Supply support for LM2676S-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 ICs, with decades of expertise in high-reliability power conversion solutions.

The LM2676 series belongs to TI's SIMPLE SWITCHER® portfolio, designed specifically for ease-of-use in cost-sensitive, medium-power DC-DC applications where minimal external components and proven reliability are critical.

FAQ

What is the maximum input voltage rating for LM2676S-12?

The absolute maximum input voltage for LM2676S-12 is 45V, but the recommended operating range is 8V to 40V. Exceeding 40V continuously risks exceeding thermal limits or violating safe operating area margins, especially under high load. Always include input transient protection if surge-prone sources (e.g., automotive or industrial lines) are used with LM2676S-12.

Does LM2676S-12 require an external catch diode?

Yes, LM2676S-12 requires an external Schottky diode connected from the SW pin (pin 1) to GND (pin 4). The device uses a nonsynchronous buck architecture with a single internal high-side DMOS switch; the diode provides the return path for inductor current during switch-off periods. A 3A, 40V Schottky (e.g., SS34) is commonly used and specified in TI's reference designs for LM2676S-12.

How is the output voltage set on LM2676S-12?

LM2676S-12 has an internally trimmed 12V feedback divider, so no external resistors are needed. Pin 6 (FB) must be connected directly to the output capacitor's positive terminal. This fixed-ratio configuration eliminates resistor tolerance errors and simplifies layout - a key distinction from the adjustable LM2676 version, which requires two external resistors to set V_OUT.

What thermal considerations apply to LM2676S-12 in TO-263 (KTW) package?

For LM2676S-12 in KTW package, the exposed thermal pad (DAP) must be soldered to a minimum 0.4896 in² (3.16 cm²) copper area on the PCB to achieve R_θJA = 35°C/W. Without adequate copper, junction temperature can exceed 125°C at full 3A load. TI recommends 12 thermal vias under the DAP connected to an inner ground plane - this is mandatory for reliable operation above 2A in ambient >60°C, as verified in LM2676S-12 thermal characterization reports.

Can LM2676S-12 be synchronized to an external clock?

No, LM2676S-12 does not support external synchronization. It uses an internal fixed-frequency 260kHz oscillator with ±11% tolerance. Unlike newer regulators (e.g., LM5143), there is no SYNC pin or frequency-adjust capability. For noise-sensitive systems requiring EMI reduction, designers must rely on input/output filtering or select alternative parts with sync capability - LM2676S-12 operates autonomously and cannot be slaved to an external timing source.