Texas Instruments SN74126N

Overview

SN74126N from Texas Instruments is a quad bus buffer with 3-state outputs, designed for bidirectional data bus isolation in TTL-level digital systems. It features independent active-low output enable (G) per channel, 16 mA low-level output drive, 5 V supply operation, and 18 ns typical propagation delay. It enables clean bus sharing in legacy industrial control backplanes and microprocessor address/data buses.

For engineers reviewing the SN74126N datasheet, SN74126N pinout, SN74126N application, or SN74126N equivalent, this page delivers verified electrical specs, package-validated pin functions, real-world use cases in bus arbitration and level translation, and two confirmed alternative parts with documented functional and timing differences.

Technical Context

The SN74126N implements four independent non-inverting buffers, each with an active-low 3-state output enable (G). When G is low, the output follows input A; when G is high, the output enters high-impedance state. Its totem-pole output stage provides TTL-compatible VOH ≥ 2.4 V at IOH = –2 mA and VOL ≤ 0.4 V at IOL = 16 mA under VCC = 5 V.

It operates across 0°C to 70°C, supports 4.75–5.25 V supply range, and exhibits tPLH/tPHL ≤ 13/18 ns (RL = 400 Ω, CL = 50 pF). The device uses standard bipolar TTL process-distinct from LS variants-and draws up to 62 mA ICC (all outputs enabled, '126 logic).

Key Specifications

Pinout & Package

SN74126N is housed in a 14-pin plastic dual in-line package (PDIP-N), 0.300-inch wide body, with standard through-hole mounting and JEDEC MO-019 compliant footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74126N, SN74LS126AN reduces power by >80% but trades 30% higher enable/disable latency, while SN74ALS126N delivers 30% faster switching at one-sixth the quiescent current-both retain identical pinout and logic function.

Availability

SN74126N is available at Aetrix Electronics and suitable for industrial backplane bus isolation, microprocessor address latching, and legacy test equipment signal routing requiring stable component supply and long-term obsolescence management.

Supply support for SN74126N 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 founded in 1930, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74xx series was TI's foundational TTL logic family, engineered for robustness, interoperability, and ease of use in commercial and industrial digital systems from the 1970s onward.

FAQ

What is the logic function of SN74126N?

SN74126N contains four independent non-inverting buffers, each with an active-low 3-state output enable (G). When G is low, Y = A; when G is high, Y is high-impedance. This matches the '126 logic type defined in TI's SDLS044A datasheet.

Does SN74126N support 3.3 V operation?

No. SN74126N is a standard TTL device requiring 4.75–5.25 V supply. It lacks 3.3 V compatibility; attempting 3.3 V operation results in undefined logic levels and insufficient output drive. Use SN74LVC126A for 3.3 V systems.

What is the maximum capacitive load SN74126N can drive?

SN74126N is characterized up to 50 pF load capacitance with RL = 400 Ω. While it can drive heavier loads, propagation delay increases linearly beyond that point; for >100 pF, consider adding series termination or using a driver with higher IOL.

Is SN74126N pin-compatible with SN74LS126AN?

Yes. Both SN74126N and SN74LS126AN use identical PDIP-14 packaging and share identical pin assignments for G, A, Y, VCC, and GND. However, their electrical behavior differs in drive strength, power consumption, and timing.

Can SN74126N be used in place of SN74125N?

No. SN74126N has active-low enable (G), while SN74125N has active-high enable. Swapping them causes inverted bus control behavior-outputs will enable/disable opposite to intended logic. Always verify enable polarity in schematic capture.