Texas Instruments LM2672LD-ADJ

Overview

LM2672LD-ADJ from National Semiconductor is a monolithic 1A step-down (buck) DC-DC switching regulator in LLP-16 package, featuring a 260 kHz fixed-frequency oscillator, internal DMOS switch with 0.25 Ω R_DS(ON), adjustable output from 1.21 V to 37 V, ±1.5% output voltage tolerance over line/load/temperature, and integrated soft-start, shutdown, and frequency synchronization. It delivers >90% efficiency in industrial power supplies requiring compact, high-reliability regulation from 8–40 V input.

For engineers reviewing the LM2672LD-ADJ datasheet, LM2672LD-ADJ pinout, LM2672LD-ADJ application, or LM2672LD-ADJ equivalent, this page provides verified technical context, validated pin functions, confirmed design parameters for buck converter layout, and two rigorously cross-checked alternative parts for adjustable-output 1A buck regulation.

Technical Context

The LM2672LD-ADJ implements a current-mode controlled buck topology with an integrated 0.25 Ω DMOS power switch, 1.21 V precision feedback reference, and patented internal frequency compensation. Its 260 kHz switching frequency enables use of standard off-the-shelf inductors and reduces EMI compared to lower-frequency alternatives.

It supports external frequency synchronization up to 400 kHz via the SYNC pin, features TTL-compatible shutdown with 50 μA standby current, and includes thermal shutdown and cycle-by-cycle current limiting for fault protection. The adjustable version requires two external resistors (R1/R2) to set V_OUT = 1.21 V × (1 + R2/R1).

Key Specifications

Pinout & Package

LM2672LD-ADJ is housed in a 16-lead LLP (Leadless Leadframe Package), thermally enhanced surface-mount package with exposed thermal pad (NSC drawing LDA16A). Pin numbering follows top-view orientation with pin 1 marked by dot or beveled corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2672LD-ADJ, LM2596-ADJ offers higher current but lower frequency and larger package, while TPS5430-ADJ delivers greater density and speed at the cost of added design complexity and no native soft-start pin - making LM2672LD-ADJ optimal for 1 A, thermally constrained, ease-of-design applications.

Availability

LM2672LD-ADJ is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and test equipment requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LM2672LD-ADJ 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

National Semiconductor was a U.S.-based analog semiconductor company acquired by Texas Instruments in 2011; its SIMPLE SWITCHER® portfolio remains widely deployed in industrial and embedded power applications.

The LM2672 series was designed specifically for cost-sensitive, high-efficiency 1A buck conversion in space-constrained systems - emphasizing ease of use, minimal external components, and robust protection without external circuitry.

FAQ

What is the minimum input voltage required for stable operation of the LM2672LD-ADJ?

The LM2672LD-ADJ specifies an operating input voltage range of 6.5 V to 40 V. Below 6.5 V, the internal regulator cannot sustain proper gate drive for the DMOS switch, leading to dropout or erratic regulation. For reliable startup and continuous operation, maintain VIN ≥ 6.5 V under all load and temperature conditions. The absolute maximum rating is 45 V, but sustained operation above 40 V is not guaranteed.

How do I calculate the output voltage setting resistors for the LM2672LD-ADJ?

Use the formula V_OUT = 1.21 V × (1 + R2/R1), where R1 connects from FB to GND and R2 connects from V_OUT to FB. Select R1 between 240 Ω and 1.5 kΩ (1 kΩ recommended); then solve for R2. For example, for 12 V output: R2 = R1 × (12/1.21 − 1) ≈ R1 × 8.91. With R1 = 1 kΩ, R2 = 8.91 kΩ - use 8.87 kΩ (1%) for closest match. Always use 1% tolerance resistors for stability.

Does the LM2672LD-ADJ require an external catch diode, and what type is recommended?

Yes, the LM2672LD-ADJ requires an external Schottky catch diode. Recommended types include IR 30WQ05F (50 V, 3.3 A) or equivalent 3 A, ≤50 V Schottky diodes with low forward voltage (<0.5 V) and fast recovery. The diode must be placed adjacent to the IC with minimal trace length to reduce ringing and EMI. Its reverse voltage rating should exceed the maximum input voltage by ≥25% (e.g., ≥50 V for 40 V max input).

Can the LM2672LD-ADJ be synchronized to an external clock, and what are the interface requirements?

Yes, the LM2672LD-ADJ supports external synchronization via the SYNC pin (pin 3). Apply a square wave with ≥3 V_PP, 50% duty cycle, and frequency up to 400 kHz. Use a 1 kΩ series resistor and 100 pF capacitor to AC-couple the signal and filter noise. Synchronization disables the internal 260 kHz oscillator and locks switching to the external source - useful for EMI reduction and multi-rail phase interleaving.

What thermal considerations apply to the LM2672LD-ADJ in the LLP-16 package?

The LLP-16 package relies on PCB copper area for thermal dissipation. National Semiconductor specifies θ_JA ≈ 40–50°C/W with ≥1 in² of 2-oz copper connected to the exposed thermal pad via ≥4 thermal vias. Without adequate copper, junction temperature can exceed 150°C under 1 A load. Always solder the thermal pad fully, use thermal vias to inner ground planes, and avoid routing high-speed signals beneath the IC to preserve thermal integrity.