Texas Instruments SN74AHC126DR

Overview

SN74AHC126DR from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for digital signal routing and bus isolation in 2V–5.5V systems. It delivers 3.8 ns typical propagation delay at 5 V, supports ±25 mA output drive, and operates across –40°C to +85°C for industrial applications including data bus control and LED driving.

For engineers reviewing the SN74AHC126DR datasheet, SN74AHC126DR pinout, SN74AHC126DR application, or SN74AHC126DR equivalent, key selection criteria include 3-state output timing (tPLH/tPHL), supply voltage flexibility (2–5.5 V), thermal performance in SOIC-14, and compatibility with TTL/CMOS logic families in mixed-voltage designs.

Technical Context

The SN74AHC126DR implements four identical non-inverting buffer channels, each with separate active-low output enable (OE) control. Its CMOS architecture ensures balanced high/low drive strength and rail-to-rail output swing, enabling bidirectional bus management without external pull-ups.

Each channel follows the Boolean function Y = A when OE is low; otherwise, the output enters high-impedance state. Input transition rate must be ≤20 ns/V at 5 V to prevent excessive power dissipation or oscillation, per TI's recommended operating conditions.

Key Specifications

Pinout & Package

SN74AHC126DR uses a 14-pin SOIC (D) package measuring 8.65 mm × 3.91 mm (body), with standard 1.27 mm pitch and gull-wing leads. Thermal pad is not present; mounting follows JEDEC MS-012.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC126APWR and 74AHC126PW, SN74AHC126DR offers broader voltage compatibility (2–5.5 V), industrial temperature rating, and active SOIC-14 supply-making it the preferred choice for mixed-voltage industrial control and upgradeable embedded systems.

Availability

SN74AHC126DR is available at Aetrix Electronics and suitable for industrial bus isolation, LED driver interface, digital signal enable/disable, and transmission line termination requiring stable component supply across extended temperature ranges and multi-vendor sourcing strategies.

Supply support for SN74AHC126DR 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 experience in logic IC design and industrial-grade reliability validation.

The SN74AHC126DR belongs to TI's AHC advanced high-speed CMOS logic family, engineered for low-power, high-noise-immunity digital interfacing in industrial automation, test equipment, and programmable logic systems.

FAQ

What is the maximum output current rating for SN74AHC126DR?

The SN74AHC126DR supports ±8 mA continuous output current per channel at 5 V, as specified in the Electrical Characteristics table under IOL and IOH conditions. This rating ensures reliable drive of standard TTL loads or up to 10 CMOS inputs. Exceeding this current may cause thermal stress or violate absolute maximum ratings, so external current limiting is advised for heavier loads.

Does SN74AHC126DR support 2.5 V operation?

Yes, SN74AHC126DR is fully specified for 2.5 V operation per its Recommended Operating Conditions: VCC min = 2 V, VIH = 1.7 V, VIL = 0.7 V at 2.5 V. Switching characteristics (e.g., tPLH ≈ 5.3 ns) and output drive (±4 mA) remain valid, making it suitable for mixed-voltage systems integrating 2.5 V FPGAs or ASICs.

How should unused inputs be handled on SN74AHC126DR?

All unused inputs on SN74AHC126DR-including A and OE pins-must be terminated to either VCC or GND using a 10-kΩ resistor or direct connection. Floating CMOS inputs risk increased power consumption, oscillation, or latch-up. The TI application report SCBA004 explicitly mandates this practice to ensure stable device behavior across temperature and voltage extremes.

Is SN74AHC126DR pin-compatible with older 74LS126 devices?

No, SN74AHC126DR is not pin-compatible with 74LS126. While both are quadruple 3-state buffers in 14-pin packages, the pin functions differ: SN74AHC126DR uses individual OE inputs (pins 1, 4, 10, 13), whereas 74LS126 has dual shared OE inputs (pins 1 and 13). Direct replacement would require PCB redesign and logic-level revalidation.

What is the thermal resistance (RθJA) of SN74AHC126DR in SOIC-14 package?

The junction-to-ambient thermal resistance (RθJA) for SN74AHC126DR in the SOIC-14 (D) package is 124.6°C/W, as documented in Section 5.4 Thermal Information. This value assumes standard JEDEC 2S2P board conditions and guides heatsinking decisions for sustained operation near maximum ambient temperature (85°C) and load.