Texas Instruments SN74ALVC126DR

Overview

SN74ALVC126DR from Texas Instruments is a quadruple bus buffer gate with 3-state outputs, designed for 1.65 V to 3.6 V V_CC operation. It provides four independent non-inverting buffers, each with dedicated output-enable (OE) control, ±24-mA drive strength at 3.3 V, and 3.1 ns max propagation delay - enabling high-speed bidirectional data bus isolation in low-voltage digital systems such as FPGA I/O expansion and memory interface buffering.

For engineers reviewing the SN74ALVC126DR datasheet, SN74ALVC126DR pinout, SN74ALVC126DR application, or SN74ALVC126DR equivalent, key selection criteria include its 14-pin SOIC (D) package, rail-to-rail input compatibility across 1.65–3.6 V, guaranteed 3-state leakage < ±10 µA, JESD 17 latch-up immunity (>250 mA), and ESD robustness per JESD 22 (2000-V HBM).

Technical Context

This device implements four independent CMOS buffer stages, each with active-high output-enable logic: when OE is low, the corresponding Y output enters high-impedance state; when OE is high, Y follows A with non-inverting logic. All inputs tolerate voltages up to V_CC + 0.5 V, supporting mixed-voltage interfacing without level shifters.

It operates within -40°C to +85°C ambient, draws only 10 µA typical ICC at 3.6 V with all inputs static, and features input transition rate tolerance of 5 ns/V - ensuring reliable timing under slow-edge or noisy signal conditions common in board-level interconnects.

Key Specifications

Pinout & Package

SN74ALVC126DR is supplied in a 14-pin SOIC (D) package, 8.75 mm × 3.91 mm body size, 1.75 mm max height, with 1.27 mm pitch gull-wing leads. Pin 1 is located at the top-left corner adjacent to the index notch or beveled edge.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus buffer applications.

Compared with SN74LVC126APWR and 74AUP1G125GW,125, the SN74ALVC126DR delivers optimal balance of speed (3.1 ns), drive strength (±24 mA), and SOIC compatibility - making it preferred for high-density, high-throughput digital backplanes requiring proven manufacturability and thermal performance (θ_JA = 86°C/W).

Availability

SN74ALVC126DR is available at Aetrix Electronics and suitable for FPGA I/O expansion, memory interface buffering, and industrial PLC backplane interface applications requiring stable component supply, long-term lifecycle assurance, and full traceability.

Supply support for SN74ALVC126DR 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The SN74ALVC126DR belongs to TI's ALVC (Advanced Low-Voltage CMOS) logic family, engineered for high-speed, low-power, 1.65–3.6 V operation in space- and power-constrained digital systems.

FAQ

What is the recommended power-up sequence for SN74ALVC126DR to avoid bus contention?

TI specifies that OE inputs must be held low (via pulldown resistors to GND) during power-up to guarantee all outputs remain in high-impedance state until V_CC stabilizes. For SN74ALVC126DR, a 10-kΩ pulldown on each OE pin ensures safe initialization without requiring external sequencers or reset controllers.

Does SN74ALVC126DR support mixed-voltage operation between 1.8-V and 3.3-V domains?

Yes. SN74ALVC126DR accepts input voltages from 0 V to V_CC + 0.5 V, allowing 3.3-V signals to safely drive its inputs when powered at 1.8 V - eliminating external level shifters in many mixed-supply designs. Output swing remains rail-to-rail (0 V to V_CC), so level translation occurs inherently at the output stage.

What is the maximum capacitive load SN74ALVC126DR can drive while maintaining specified t_pd?

Per TI's SCES111J datasheet, SN74ALVC126DR's 3.1 ns max t_pd is characterized with 30-pF load at V_CC = 3.3 V. Driving >50 pF increases propagation delay nonlinearly; for loads beyond 50 pF, derating curves in Figure 1 show t_pd rises to ~5.6 ns at 1.8 V - design margin must account for this in timing-critical paths.

Can SN74ALVC126DR replace older 74LS126 devices in existing SOIC-14 layouts?

Yes. SN74ALVC126DR uses the same SOIC (D) package, pinout, and logic function as SN74LS126, with identical pin assignments for OE, A, and Y terminals. Its lower supply voltage (1.65–3.6 V vs. 4.75–5.25 V) and CMOS inputs require no layout changes - only V_CC and decoupling updates to match the new rail.

How does SN74ALVC126DR handle floating or slow-rising inputs?

All unused inputs of SN74ALVC126DR must be tied to V_CC or GND to prevent increased ICC and potential oscillation. TI's application report SCBA004 confirms that unconnected CMOS inputs cause excessive current draw and noise susceptibility - this applies directly to SN74ALVC126DR's OE and A pins, which lack internal pullups/pulldowns.