Texas Instruments SN74AHC126DBR

Overview

SN74AHC126DBR 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, ±25 mA output drive, and operates across –40°C to +85°C - enabling use in industrial control backplanes and mixed-voltage logic interfaces.

For engineers reviewing the SN74AHC126DBR datasheet, SN74AHC126DBR pinout, SN74AHC126DBR application, or SN74AHC126DBR equivalent, this page provides verified functional context, package-specific pin mapping (SSOP-14), real-world switching behavior under 15 pF/50 pF loads, and validated alternatives for bus buffering in space-constrained PCB layouts.

Technical Context

The SN74AHC126DBR implements four identical non-inverting buffers, each with dedicated active-low output-enable (OE) control and CMOS-compatible input thresholds. Its balanced 3-state outputs support bidirectional bus sharing by enabling/disabling signal paths without contention.

Each channel follows Y = A logic with OE = L enabling output drive and OE = H placing Y in high-impedance state. Input transition rate must be ≤20 ns/V at 5 V to prevent oscillation, and unused inputs require termination to VCC or GND per TI SCBA004 guidance.

Key Specifications

Pinout & Package

SN74AHC126DBR uses a 14-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 5.0 mm × 6.4 mm body size, and exposed thermal pad not present - suitable for reflow-soldered industrial PCBs requiring moderate I/O density and thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC126DBR, SN74LVC126APWR trades 5 V compatibility for lower voltage operation and reduced quiescent current, while 74AHC126PW,118 offers identical electrical behavior in a functionally interchangeable package - making the latter ideal for second-source assurance without layout changes.

Availability

SN74AHC126DBR is available at Aetrix Electronics and suitable for industrial automation backplanes, medical device GPIO expansion, and automated test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74AHC126DBR 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 logic solutions, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74AHC126DBR belongs to TI's AHC logic family - engineered for high-speed, low-power, 3-state bus interface applications in mixed-voltage systems where signal integrity and design flexibility are critical.

FAQ

What is the maximum recommended load capacitance for SN74AHC126DBR at 5 V supply?

The SN74AHC126DBR is characterized up to 50 pF load capacitance at 5 V, with tPLH/tPHL specified at 5.3 ns (min) and 8.5 ns (max). Driving >50 pF increases propagation delay nonlinearly and may cause ringing; for >75 pF loads, add series termination or reduce edge rate via input RC filtering.

Can SN74AHC126DBR operate reliably at 2.5 V supply voltage?

Yes, SN74AHC126DBR supports 2.5 V operation per its Recommended Operating Conditions (VCC = 2 V to 5.5 V). At 2.5 V, VOH is guaranteed ≥2.3 V and VOL ≤0.25 V with IOL = 4 mA, meeting LVTTL logic thresholds and enabling interoperability with 2.5 V FPGAs and ASICs.

How should unused inputs be handled on SN74AHC126DBR?

All unused inputs on SN74AHC126DBR must be tied to VCC or GND - never left floating - to prevent excessive ICC and potential oscillation. TI recommends 10-kΩ pull-up/down resistors for un-driven OE or A pins, as confirmed in application report SCBA004.

Does SN74AHC126DBR include internal ESD protection diodes?

Yes, SN74AHC126DBR features internal clamp diodes on all inputs (negative only) and outputs (both positive and negative), rated for ±2000 V HBM and ±1000 V CDM per JEDEC JS-001/JS-002 - eliminating need for external TVS devices in most board-level ESD protection schemes.

Is SN74AHC126DBR pin-compatible with other packages in the same family?

SN74AHC126DBR (SSOP-14) shares identical pinout with SN74AHC126PW (TSSOP-14) and SN74AHC126DR (SOIC-14), as verified in TI SCLS257N Figure 4-1 and Package Option Addendum. Mechanical dimensions differ, but PCB footprint and signal routing remain interchangeable across these variants.