Texas Instruments LM2674LD-3.3

Overview

LM2674LD-3.3 from Texas Instruments is a monolithic 500 mA step-down (buck) switching voltage regulator in LLP-16 package, delivering fixed 3.3 V output with ±1.5% tolerance over line and load, 260 kHz fixed-frequency operation, and 0.25 Ω DMOS switch. It enables high-efficiency (>90%) power conversion in industrial DC/DC supplies and embedded systems requiring compact, thermally efficient regulation.

For engineers reviewing the LM2674LD-3.3 datasheet, LM2674LD-3.3 pinout, LM2674LD-3.3 application, or LM2674LD-3.3 equivalent, key selection criteria include input voltage range (6.5–40 V), guaranteed 500 mA load capability, thermal shutdown protection, TTL-compatible shutdown control, and compatibility with standard off-the-shelf inductors and Schottky diodes.

Technical Context

The LM2674LD-3.3 integrates a 0.25 Ω DMOS power switch, internal 260 kHz oscillator, patented frequency compensation (U.S. Pat. Nos. 5,382,918 & 5,514,947), and feedback comparator referenced to 1.21 V. It operates in continuous conduction mode with up to 95% duty cycle and supports external shutdown with 50 μA standby current.

Its architecture eliminates need for external compensation components, requires only five external parts (inductor, catch diode, input/output capacitors, boost capacitor), and relies on copper PCB traces as sole heat sink due to >90% efficiency - enabling compact, low-BOM-count buck converter designs without heatsinks.

Key Specifications

Pinout & Package

LM2674LD-3.3 is housed in a 16-lead LLP (Leadless Leadframe Package) with exposed thermal pad, optimized for surface-mount assembly and enhanced thermal dissipation. Pin numbering follows TI's LDA16A package drawing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2674LD-3.3, LM2675SD-3.3 offers higher current headroom in SO-8, while TPS54331DR provides greater flexibility at the cost of increased external component count and layout sensitivity - making LM2674LD-3.3 optimal for cost-sensitive, thermally constrained 500 mA fixed-output applications.

Availability

LM2674LD-3.3 is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, point-of-load telecom converters, and medical diagnostic instruments requiring stable component supply and long-term production continuity.

Supply support for LM2674LD-3.3 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 and embedded processing technologies, with decades of expertise in power management ICs.

The LM2674 series belongs to TI's SIMPLE SWITCHER® portfolio - designed specifically for ease-of-use, high-efficiency, and minimal external component count in non-isolated DC/DC buck converter applications.

FAQ

What is the maximum input voltage rating for LM2674LD-3.3?

The absolute maximum input voltage for LM2674LD-3.3 is 45 V, but the recommended operating range is 6.5 V to 40 V DC. Operation above 40 V risks exceeding safe junction temperature or violating SOA limits, even with proper thermal design. The device is commonly used with 12 V, 24 V, and 36 V industrial inputs - all well within its specified range. Always verify transient conditions (e.g., load dump) against the 45 V absolute max.

Does LM2674LD-3.3 require external compensation components?

No, LM2674LD-3.3 does not require external compensation components. It incorporates patented internal frequency compensation (U.S. Pat. Nos. 5,382,918 and 5,514,947), enabling stable operation with only five external parts: input capacitor, output capacitor, inductor, catch diode, and boost capacitor. This simplifies design, reduces bill-of-materials cost, and eliminates tuning iterations - a key advantage over many adjustable or non-compensated buck controllers.

What package type is used for LM2674LD-3.3, and how is thermal performance managed?

LM2674LD-3.3 uses a 16-lead LLP (Leadless Leadframe Package) with an exposed thermal pad (TI package code LDA16A). Thermal performance relies on soldering the EPAD to a large copper area on the PCB - typically ≥1 in² - which serves as the primary heat sink. With >90% efficiency, copper traces alone dissipate heat effectively; no additional heatsink is needed. Thermal resistance (θ_JA) depends on PCB layout - refer to TI Application Note AN-1187 for optimized thermal vias and copper fill guidelines.

Can LM2674LD-3.3 be used with ceramic output capacitors?

LM2674LD-3.3 is compatible with ceramic output capacitors, but caution is advised. The datasheet recommends tantalum or low-ESR electrolytic capacitors for stability and ripple suppression. Ceramic capacitors may cause ringing at the SW node due to low ESR and parasitic inductance - especially if layout is suboptimal. If ceramics are used, add a small series resistor (e.g., 10–50 mΩ) or parallel RC snubber near the output to dampen oscillation, and verify stability across line/load/temperature per Figure 2 test circuit.

What is the purpose of the BOOST pin on LM2674LD-3.3?

The BOOST pin on LM2674LD-3.3 provides the gate-drive voltage for the internal DMOS high-side switch. It must be connected via a 0.01 μF, 50 V ceramic capacitor between BOOST and the SW (switch node) pin. This forms a bootstrap circuit that elevates the gate voltage above VIN during switch conduction, ensuring full enhancement of the integrated MOSFET. Omitting or misrouting this capacitor causes weak switching, excessive R_DS(ON), thermal runaway, and potential device failure - it is mandatory for proper operation of LM2674LD-3.3.