Texas Instruments SN74LVTH126NS

Overview

SN74LVTH126NS from Texas Instruments is a quad 3-state noninverting buffer with bus-hold circuitry, designed for 3.3-V V_CC operation while interfacing to 5-V TTL systems. It supports mixed-mode signal operation (5-V inputs/outputs with 3.3-V supply), features I_off and power-up 3-state for hot insertion, and operates down to 2.7 V for unregulated battery applications.

For engineers reviewing the SN74LVTH126NS datasheet, SN74LVTH126NS pinout, SN74LVTH126NS application, or SN74LVTH126NS equivalent, key selection criteria include its 14-pin SO (NS) package, 2.7–3.6-V supply range, ±100 µA I_off, bus-hold on all data inputs, and guaranteed 3.8 ns typical propagation delay at 3.3 V.

Technical Context

The SN74LVTH126NS implements four independent noninverting buffers, each with an active-high output-enable (OE) control input. Its bus-hold circuitry actively maintains undriven inputs at valid logic levels without external resistors, eliminating floating-input risks in high-impedance bus environments.

It integrates I_off protection to disable outputs during power-down and power-up 3-state logic that forces outputs into high-impedance when V_CC is below 1.5 V-critical for hot-swap compliance and preventing backdrive current in partial-power systems.

Key Specifications

Pinout & Package

The SN74LVTH126NS is housed in a 14-pin plastic small-outline (SO) package per JEDEC MO-194, with 0.150-inch body width, 1.75-mm lead pitch, and gull-wing leads. Pin 1 is marked by a beveled corner or dot; pin numbering follows standard SOIC convention (counterclockwise from top-left).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 3-state buffer applications.

Compared with SN74LVC126A and SN74ALVC126, the SN74LVTH126NS uniquely combines bus-hold, I_off, and 5-V-tolerant I/O in a single 3.3-V device - making it the only option for legacy bus interfaces requiring zero-external-component stability and live insertion.

Availability

SN74LVTH126NS is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control units, hot-swappable test equipment carriers, and legacy system upgrades requiring stable component supply across extended product lifecycles.

Supply support for SN74LVTH126NS 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, embedded processing, and connectivity technologies, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74LVTH126NS belongs to TI's LVTH logic family, engineered specifically for mixed-voltage system interoperability - delivering robust 3.3-V core operation with seamless 5-V signal compatibility in space-constrained industrial and automotive applications.

FAQ

What is the maximum input voltage the SN74LVTH126NS can tolerate on its A pins?

The SN74LVTH126NS accepts input voltages up to 5.5 V on its data (A) and output-enable (OE) pins, regardless of V_CC level. This 5-V tolerance allows direct connection to legacy TTL buses without external clamping diodes or level shifters, and is explicitly specified in the Absolute Maximum Ratings table of the SCBS746B datasheet.

Does the SN74LVTH126NS require external pullup or pulldown resistors on its inputs?

No, the SN74LVTH126NS does not require external pullup or pulldown resistors because it integrates active bus-hold circuitry on all data (A) inputs. This feature maintains undriven inputs at their last-valid logic state, eliminating floating nodes and associated noise susceptibility - a key design advantage confirmed in the Functional Description section of the datasheet.

Can the SN74LVTH126NS be used in hot-insertion applications?

Yes, the SN74LVTH126NS is explicitly designed for hot-insertion applications via two complementary features: I_off circuitry disables outputs during power-down to prevent backdrive current, and power-up 3-state forces outputs into high-impedance when V_CC is between 0 and 1.5 V - both verified in the Datasheet's "description/ordering information" and "Functional Description" sections.

What is the thermal resistance (θ_JA) of the SN74LVTH126NS in its NS package?

According to the Absolute Maximum Ratings table in the SCBS746B datasheet, the SN74LVTH126NS in the 14-pin SO (NS) package has a junction-to-ambient thermal resistance (θ_JA) of 76 °C/W. This value is measured under standard JEDEC conditions and supports reliable operation in industrial ambient temperatures up to +85°C with appropriate PCB copper area.

How many independent buffers does the SN74LVTH126NS contain, and what is their logic function?

The SN74LVTH126NS contains four independent noninverting buffers, each with its own data input (A), output (Y), and active-high output-enable (OE) control. As confirmed in the Logic Diagram and Function Table of the SCBS746B datasheet, each buffer passes A to Y unchanged when OE is high, and places Y in high-impedance when OE is low - enabling flexible bus sharing and load isolation.