Texas Instruments LM2670T-3.3/NOPB

Overview

LM2670T-3.3/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 3 A output current with fixed 3.3 V output, 8–40 V input range, ±2% output voltage tolerance, and 260 kHz internal switching frequency. It integrates a 150 mΩ DMOS high-side switch and supports external clock synchronization for EMI control in communications equipment.

For engineers reviewing the LM2670T-3.3/NOPB datasheet, LM2670T-3.3/NOPB pinout, LM2670T-3.3/NOPB application, or LM2670T-3.3/NOPB equivalent, key selection criteria include its 3.3 V fixed output accuracy, 50 µA standby current in shutdown mode, thermal shutdown and current limiting protection, and TO-263-7 (KTW) package suitability for high-current industrial power supplies.

Technical Context

The LM2670T-3.3/NOPB implements a voltage-mode PWM controller with an internal 260 kHz oscillator and supports external synchronization from 280–400 kHz. Its integrated 150 mΩ DMOS high-side switch enables >90% efficiency at full load, while the feedback pin (FB) connects directly to the output for fixed-voltage regulation-no external divider required.

Functional modes include active regulation (ON/OFF ≥1.4 V) and shutdown (ON/OFF ≤0.8 V), drawing only 50 µA quiescent current. The SYNC pin accepts TTL/CMOS-compatible clocks to precisely position ripple spectrum, critical for radio and comms systems where EMI filtering must be deterministic.

Key Specifications

Pinout & Package

LM2670T-3.3/NOPB is packaged in TO-263-7 (KTW), a thermally enhanced surface-mount variant of the DDPAK with exposed thermal pad. The 10.1 mm × 15.24 mm footprint supports high-current PCB layouts with direct thermal coupling to copper planes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2596T-3.3/NOPB and TPS54302DDAR, the LM2670T-3.3/NOPB uniquely combines 3 A capability, 8–40 V input range, SYNC functionality, and TO-263 thermal performance-making it the only option among the three for ruggedized, EMI-controlled, medium-power industrial buck conversion.

Availability

LM2670T-3.3/NOPB is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and automotive body electronics requiring stable component supply, long-term manufacturability, and proven thermal reliability in high-ambient environments.

Supply support for LM2670T-3.3/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 ICs, with decades of expertise in high-reliability power conversion solutions.

The LM2670 series belongs to TI's SIMPLE SWITCHER® portfolio-designed specifically for engineers needing robust, easy-to-implement DC-DC buck regulators with minimal external components and industry-leading thermal performance.

FAQ

What is the maximum input voltage rating for LM2670T-3.3/NOPB?

The absolute maximum input voltage for LM2670T-3.3/NOPB is 45 V, but the recommended operating range is 8 V to 40 V per the datasheet. Exceeding 40 V risks violating safe operating area limits and may trigger internal protection circuits. For sustained operation, keep VIN ≤40 V-this ensures reliable performance across temperature and load extremes while preserving long-term reliability of the internal DMOS switch.

Does LM2670T-3.3/NOPB require external feedback resistors to set its output voltage?

No, LM2670T-3.3/NOPB does not require external feedback resistors. As a fixed-output variant, it has internal precision resistors connecting the FB pin to an internal 3.3 V reference. The FB pin must be connected directly to the output capacitor node-no divider network is needed. This eliminates resistor tolerance errors and thermal drift effects, contributing to the ±2% output voltage accuracy over temperature and load.

Can LM2670T-3.3/NOPB synchronize to an external clock, and what is the valid frequency range?

Yes, LM2670T-3.3/NOPB supports external synchronization via the SYNC pin (Pin 5). The valid input clock frequency range is 280 kHz to 400 kHz-strictly higher than the internal oscillator's maximum of 280 kHz. Using a lower-frequency external clock may cause erratic operation or failure to lock. The SYNC signal must be TTL/CMOS compatible (0 V to >3 V) and AC-coupled with a 100 pF capacitor and 1 kΩ pull-down resistor per TI's recommended interface.

What thermal performance can be expected from LM2670T-3.3/NOPB in its TO-263-7 package?

In the TO-263-7 (KTW) package, LM2670T-3.3/NOPB achieves a junction-to-ambient thermal resistance (R_θJA) of 35°C/W with 0.4896 in² (3.6× package area) of 1 oz copper, and as low as 26°C/W with 1.0064 in² (7.4× package area) of copper plus thermal vias. The exposed thermal pad must be soldered to a solid ground plane-failure to do so degrades thermal performance by >40% and risks thermal shutdown under 3 A load at elevated ambient temperatures.

How does the ON/OFF pin function on LM2670T-3.3/NOPB, and what voltage levels enable or disable regulation?

The ON/OFF pin (Pin 7) controls device enable state: a voltage ≥1.4 V enables regulation (active mode), while ≤0.8 V forces shutdown mode with 50 µA standby current. The pin features a 20 µA internal pull-up and 7 V Zener clamp. Driving it directly with a microcontroller GPIO is safe if limited to ≤6 V; floating the pin enables the regulator by default. This logic-level interface simplifies integration into power sequencing architectures without level-shifting circuitry.