Texas Instruments SN74ALVC126NSR

Overview

SN74ALVC126NSR 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 features four independent non-inverting drivers, each controlled by a dedicated output-enable (OE) input, delivering ±24-mA drive strength at 3.3 V and 3.1-ns max propagation delay. It is used in bidirectional data bus isolation and level translation between mixed-voltage subsystems in industrial control and embedded communication interfaces.

For engineers reviewing the SN74ALVC126NSR datasheet, SN74ALVC126NSR pinout, SN74ALVC126NSR application, or SN74ALVC126NSR equivalent, key selection criteria include 3-state output timing consistency across supply voltages, latch-up immunity (>250 mA), ESD robustness (2000-V HBM), and compatibility with 14-pin SOP (NS) PCB footprints.

Technical Context

This device implements four identical non-inverting buffer channels, each with separate active-low output-enable control. Each channel transitions to high-impedance when its OE input is low, enabling bus sharing without contention. The logic diagram confirms positive-logic inputs and outputs with no internal inversion.

It operates across a wide 1.65–3.6-V supply range, supporting mixed-voltage system interfacing. Input thresholds scale with V_CC (e.g., V_IL = 0.35×V_CC at 1.65 V), and output drive capability increases with supply voltage - up to ±24 mA at 3.0 V - ensuring reliable signal integrity under load.

Key Specifications

Pinout & Package

SOP (NS) package: 14-pin plastic small-outline package, 8.1 mm × 10.4 mm body size, 1.27 mm pitch, 1.75 mm max height, RoHS-compliant NIPDAU lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALVC126NSR, SN74LVC126APWRE4 offers marginally faster timing in same-package form factor, while 74ALVC126MTCX provides second-source availability with slightly reduced ESD robustness - both require validation of OE pin behavior and thermal impedance in high-density layouts.

Availability

SN74ALVC126NSR is available at Aetrix Electronics and suitable for industrial PLC backplanes, low-power sensor hubs, USB-to-parallel bridges, and legacy display controller interfaces requiring stable component supply and long-term manufacturability.

Supply support for SN74ALVC126NSR 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, specializing in analog, embedded processing, and connectivity technologies with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74ALVC126NSR belongs to TI's ALVC (Advanced Low-Voltage CMOS) logic family, engineered for low-voltage, high-speed bus interface applications in space-constrained and power-sensitive embedded systems.

FAQ

What is the recommended power-up sequence for SN74ALVC126NSR to avoid bus contention?

TI recommends tying all OE pins to GND through a pulldown resistor (value determined by driver sourcing capability) during power-up to ensure outputs remain in high-impedance until V_CC stabilizes. This prevents undefined states on shared buses. The SN74ALVC126NSR datasheet specifies that OE must be held low until V_CC reaches valid operating range; no external reset sequencing is required beyond this passive pulldown for the SN74ALVC126NSR.

Can SN74ALVC126NSR safely interface a 1.8-V microcontroller with a 3.3-V ADC?

Yes - the SN74ALVC126NSR supports 1.65–3.6-V V_CC, and its inputs are 3.6-V tolerant regardless of supply voltage. When powered at 3.3 V, it accepts 1.8-V logic-high inputs and drives 3.3-V compatible outputs. This makes the SN74ALVC126NSR ideal for unidirectional signal translation from low-voltage controllers to higher-voltage data converters without level-shifting circuitry.

Does SN74ALVC126NSR require external pull-up or pull-down resistors on unused inputs?

Yes - TI mandates that all unused inputs (A and OE pins) be tied to either V_CC or GND to prevent floating nodes, which can cause increased ICC, noise susceptibility, or erratic output behavior. The SN74ALVC126NSR datasheet references application report SCBA004 for implementation guidance; typical values are 10-kΩ pull-up/down resistors, confirmed for the SN74ALVC126NSR in production designs.

What is the thermal resistance (θ_JA) of SN74ALVC126NSR in its SOP (NS) package?

The SN74ALVC126NSR in the SOP (NS) package has a junction-to-ambient thermal resistance (θ_JA) of 76°C/W under standard JEDEC conditions. This value assumes a two-layer PCB with 1-in² copper pour; actual thermal performance improves with additional copper area or internal ground/power planes. The SN74ALVC126NSR's 76°C/W rating supports continuous operation at 85°C ambient when dissipating ≤100 mW.

How does the 3-state enable timing of SN74ALVC126NSR affect bus turnaround in half-duplex interfaces?

The SN74ALVC126NSR specifies t_en (enable time) ≤3.3 ns and t_dis (disable time) ≤3.7 ns at 3.3 V, enabling sub-4-ns bus turnaround - critical for high-efficiency half-duplex protocols like SPI slave select or I²C-like arbitration. These tight timing specs allow the SN74ALVC126NSR to support >100-MHz effective bus switching without added dead-time delays in FPGA- or MCU-controlled interfaces.