Texas Instruments SN74AHCT126QDREP

Overview

SN74AHCT126QDREP from Texas Instruments is a quadruple 3-state bus buffer gate with independent enable control per channel, operating at 4.5–5.5 V supply, supporting −40°C to 125°C extended temperature range, TTL-compatible inputs, and 8 mA output drive. It enables bidirectional data isolation in industrial control backplanes and automotive body electronics.

For engineers reviewing the SN74AHCT126QDREP datasheet, SN74AHCT126QDREP pinout, SN74AHCT126QDREP application, or SN74AHCT126QDREP equivalent, key selection criteria include guaranteed 3-state leakage (±2.5 µA), propagation delay ≤6.5 ns at 15 pF, and SOIC-14 packaging qualified for harsh-environment deployment.

Technical Context

This device implements four noninverting buffer channels, each with dedicated active-high output-enable (OE) input controlling high-impedance state independently. Logic operation follows positive-logic truth table: when OE = HIGH, Y = A; when OE = LOW, Y = high-Z.

Designed for mixed-voltage system interfacing, it accepts TTL-level inputs (VIH = 2 V min, VIL = 0.8 V max) while driving CMOS loads at 5 V. Input clamp current rating (−20 mA) and output short-circuit tolerance (±20 mA) support robust noise immunity in electrically noisy environments.

Key Specifications

Pinout & Package

SN74AHCT126QDREP is housed in a 14-pin SOIC (D) package, 8.75 mm × 3.91 mm footprint, 1.75 mm max height, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT126QDREP, SN74LVC126A offers higher drive but lacks extended temperature certification, while SN74AHCT125QDREP provides identical performance with inverted enable logic-making it suitable only when system control architecture uses active-low gating.

Availability

SN74AHCT126QDREP is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, and avionics data acquisition interfaces requiring stable component supply across extended temperature and long product lifecycles.

Supply support for SN74AHCT126QDREP 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, longevity, and industrial-grade qualification.

The SN74AHCT126QDREP belongs to TI's enhanced-product (EP) logic family, engineered specifically for high-reliability applications in automotive, aerospace, and industrial automation where extended temperature operation and DMS support are mandatory.

FAQ

What is the maximum allowable input voltage for SN74AHCT126QDREP?

The absolute maximum input voltage for SN74AHCT126QDREP is −0.5 V to 7 V, as specified in the Absolute Maximum Ratings table. However, for reliable operation within recommended conditions, input voltage must remain between 0 V and VCC (4.5–5.5 V). Exceeding VCC by more than 0.5 V risks damaging the output clamp diodes, and sustained overvoltage may degrade long-term reliability even if within absolute limits.

Does SN74AHCT126QDREP require external pull-up or pull-down resistors on its OE pins?

Yes - to ensure high-impedance state during power-up or power-down, each OE pin of SN74AHCT126QDREP must be tied to GND through a pulldown resistor. The minimum resistance value depends on the current-sourcing capability of the driver controlling OE; TI recommends values between 1 kΩ and 10 kΩ for most applications. Leaving OE floating violates recommended operating conditions and may cause undefined output states.

Can SN74AHCT126QDREP interface directly with 3.3 V logic outputs?

No - SN74AHCT126QDREP inputs are TTL-voltage compatible (VIH ≥ 2 V, VIL ≤ 0.8 V), but 3.3 V logic outputs typically swing 0–3.3 V and may not reliably exceed the 2 V VIH threshold across process/voltage/temperature corners. For guaranteed compatibility, use a level translator such as SN74AVC4T245 or add a resistive divider to raise the effective VIH margin, especially in industrial temperature ranges.

What is the thermal resistance θJA for SN74AHCT126QDREP in SOIC package?

The junction-to-ambient thermal resistance (θJA) for SN74AHCT126QDREP in the SOIC (D) package is 86°C/W, measured under JEDEC JESD 51-7 standard conditions. This value assumes a two-layer PCB with 1 in² copper pour on both top and bottom layers. Actual thermal performance may vary depending on PCB layout, airflow, and adjacent heat sources - derate power dissipation accordingly in enclosed or high-ambient environments.

Is SN74AHCT126QDREP pin-compatible with standard SN74AHCT126 devices?

Yes - SN74AHCT126QDREP shares identical pinout, electrical specifications, and SOIC-14 package dimensions with the commercial-grade SN74AHCT126, differing only in extended temperature qualification (−40°C to 125°C), enhanced DMS support, and controlled baseline manufacturing. No PCB layout changes are required when upgrading from catalog to QDREP variant in new designs or field replacements.