Texas Instruments LM2670T-12/NOPB

Overview

LM2670T-12/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 3A output current with fixed 12V output, 8–40V input range, 260kHz internal oscillator, ±2% output voltage tolerance, and 94% peak efficiency at 24V_IN/3A. It serves as a high-efficiency preregulator in industrial power supplies and communications equipment.

For engineers reviewing the LM2670T-12/NOPB datasheet, LM2670T-12/NOPB pinout, LM2670T-12/NOPB application, or LM2670T-12/NOPB equivalent, key selection criteria include its 12V fixed output, TO-263-7 (KTW) thermal package, SYNC capability for ripple frequency control, and 50µA standby current in shutdown mode.

Technical Context

The LM2670T-12/NOPB integrates a 150mΩ DMOS high-side switch and PWM controller with internal 260kHz oscillator, enabling continuous-mode buck conversion without external timing components. Its feedback loop uses a direct FB-to-output connection for fixed 12V regulation and supports external synchronization from 280–400kHz to position ripple spectrum.

Functional modes include active regulation (ON/OFF ≥1.4V) and shutdown (ON/OFF ≤0.8V), with built-in thermal shutdown, cycle-by-cycle current limiting (3.6–5.4A), and 50µA quiescent draw in OFF state. The CBOOST pin requires a 100nF capacitor to gate-drive the internal MOSFET above VIN for low R_DS(ON) conduction.

Key Specifications

Pinout & Package

LM2670T-12/NOPB is packaged in TO-263-7 (KTW), a thermally enhanced surface-mount variant of the DDPAK with exposed thermal pad. The 10.1mm × 15.24mm footprint provides low R_θJA (35°C/W with 0.4896 in² copper) and requires soldering the DAP to PCB ground for optimal thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2671-12/NOPB and TPS54302DDAR, the LM2670T-12/NOPB uniquely balances 3A capability, wide 8–40V input, SYNC flexibility, and proven thermal robustness in TO-263 - making it optimal for industrial and telecom power stages where reliability and design simplicity are prioritized over ultra-small footprint.

Availability

LM2670T-12/NOPB is available at Aetrix Electronics and suitable for industrial power preregulators, communications equipment supplies, battery charger auxiliary rails, and embedded control system supplies requiring stable component supply and long-term manufacturability.

Supply support for LM2670T-12/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 company specializing in analog and embedded processing technologies, with leadership in power management ICs for industrial, automotive, and communications markets.

The LM2670 series belongs to TI's SIMPLE SWITCHER® portfolio, designed specifically to simplify high-efficiency DC-DC buck converter implementation using minimal external components while maintaining robust thermal and fault protection.

FAQ

What is the maximum input voltage rating for the LM2670T-12/NOPB?

The LM2670T-12/NOPB has an absolute maximum input voltage rating of 45V, with recommended operation between 8V and 40V. Exceeding 40V continuously risks exceeding thermal limits and degrading long-term reliability, even if within absolute max ratings. The 8–40V range ensures stable regulation and full specification compliance across temperature and load conditions for the LM2670T-12/NOPB.

Does the LM2670T-12/NOPB require external feedback resistors?

No, the LM2670T-12/NOPB does not require external feedback resistors. As a fixed 12V output variant, it contains internal precision resistor dividers connected to the FB pin. The FB pin must be shorted directly to the output capacitor's positive terminal to enable regulation - no external components are needed for voltage setting, simplifying layout and improving accuracy versus adjustable versions.

How does the SYNC function affect protection features in the LM2670T-12/NOPB?

When the SYNC pin is actively driven (280–400kHz), the LM2670T-12/NOPB disables current limit frequency foldback. This means short-circuit protection remains active via cycle-by-cycle current limiting, but the device may sustain higher peak currents during extreme faults compared to free-running mode. Designers should verify worst-case short-circuit energy dissipation and consider adding external current limiting if operating near thermal limits under SYNC.

What thermal performance can be expected from the LM2670T-12/NOPB in TO-263-7 package?

In the TO-263-7 (KTW) package, the LM2670T-12/NOPB achieves 35°C/W junction-to-ambient thermal resistance with 0.4896 in² of 1 oz copper, and as low as 26°C/W with 1.0064 in² copper plus thermal vias. Proper soldering of the exposed thermal pad to the PCB ground plane is mandatory - failure to do so degrades thermal performance by >40% and risks thermal shutdown under 3A load.

Can the LM2670T-12/NOPB operate in discontinuous conduction mode (DCM)?

Yes, the LM2670T-12/NOPB automatically transitions into discontinuous conduction mode at light loads (<~300mA at 12V). Its PWM controller maintains regulation down to zero load, and the 50µA standby current in shutdown mode is distinct from DCM operation. In DCM, efficiency drops slightly below 80% at very light loads, but output voltage remains tightly regulated - confirmed in Figure 5-4 and Figure 5-13 of the LM2670T-12/NOPB datasheet.