Texas Instruments SN74ABT623NS

Overview

SN74ABT623NS from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data communication between two 8-bit buses. It features dual output-enable controls (OEAB and OEBA), high-drive capability (–32 mA IOH / 64 mA IOL), and operates over –40°C to 85°C at 4.5–5.5 V supply. It is used in legacy industrial backplane and board-to-board interconnect systems requiring bus isolation and direction control.

For engineers reviewing the SN74ABT623NS datasheet, SN74ABT623NS pinout, SN74ABT623NS application, or SN74ABT623NS equivalent, key selection considerations include its 20-pin SO (NS) package, true bidirectional data flow, 3-state output timing (tPZH/tPLZ ≤ 7.5 ns), and compatibility with TTL-level control inputs in 5-V logic systems.

Technical Context

The SN74ABT623NS implements a dual-enable bus transceiver architecture with independent OEAB (A→B enable) and OEBA (B→A enable) inputs, enabling flexible data direction control and bus isolation. Its EPIC-II™B BiCMOS process delivers low ground bounce (VOLP < 1 V) and latch-up immunity (>500 mA per JESD-17).

It supports simultaneous bidirectional operation when both enables are active, allowing bus state retention via internal feedback - a feature critical for hold-mode applications in legacy computing and instrumentation subsystems.

Key Specifications

Pinout & Package

The SN74ABT623NS is housed in a 20-pin plastic small-outline (SO) package (NS), 7.5 mm wide, with 0.65 mm lead pitch and gull-wing leads. It complies with JEDEC MS-012 and is RoHS-compliant with green (Pb-free, no Sb/Br) finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ABT245N and SN74LVC245APW, the SN74ABT623NS uniquely supports true bidirectional bus retention via dual OE control and delivers higher drive strength in native 5-V operation - making it irreplaceable in legacy industrial backplanes requiring zero-latency bus state hold and robust noise immunity.

Availability

SN74ABT623NS is available at Aetrix Electronics and suitable for industrial backplane interconnect, legacy computer system expansion, test equipment signal routing, and automated manufacturing fixture interface requiring stable component supply and long-term obsolescence management.

Supply support for SN74ABT623NS 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 decades of heritage in industrial and automotive-grade components.

The SN74ABT623NS belongs to TI's ABT-series advanced bipolar transistor logic family, engineered for high-speed, high-drive 5-V bus interfacing in mission-critical industrial and instrumentation systems.

FAQ

What is the maximum operating temperature range for the SN74ABT623NS?

The SN74ABT623NS is rated for operation from –40°C to +85°C. This industrial temperature range ensures reliable performance in demanding environments such as factory automation controllers and test equipment enclosures where ambient temperatures may fluctuate significantly. The SN74ABT623NS specification sheet confirms this range under "recommended operating conditions" and distinguishes it from the military-grade SN54ABT623A variant.

Does the SN74ABT623NS support true bidirectional data flow without external direction logic?

Yes, the SN74ABT623NS supports true bidirectional data flow using its dual output-enable inputs OEAB and OEBA. When OEAB is low and OEBA is high, data flows from A to B; when OEBA is low and OEAB is high, data flows from B to A; and when both are low, data flows bidirectionally. This eliminates the need for external direction-control logic, simplifying design in systems like modular backplanes where dynamic bus arbitration is required.

What is the recommended power-up sequence to ensure high-impedance outputs on the SN74ABT623NS?

To guarantee high-impedance outputs at power-up, OEBA must be tied to VCC through a pullup resistor and OEAB must be tied to GND through a pulldown resistor. The minimum resistor values depend on driver current-sinking and sourcing capabilities - typically 10 kΩ suffices. This configuration prevents bus contention during power ramp-up, a requirement explicitly stated in the SN74ABT623NS datasheet's application guidance section.

Can the SN74ABT623NS be used in place of the SN74ABT623DBR or SN74ABT623DWR?

Yes, the SN74ABT623NS is functionally identical to SN74ABT623DBR and SN74ABT623DWR but differs only in package: NS is a 20-pin SOIC with 0.65 mm pitch and 7.5 mm body width, while DBR uses SSOP and DWR uses wider SOIC (DW). Pinout, electrical specs, timing, and thermal characteristics are fully aligned. Board layout changes are required due to mechanical differences, but no schematic or firmware modifications are needed for substitution.

What is the typical output ground bounce (VOLP) specification for the SN74ABT623NS?

The SN74ABT623NS exhibits typical output ground bounce (VOLP) of less than 1 V at VCC = 5 V and TA = 25°C, as confirmed in the "Features" section of its official datasheet. This low VOLP results from TI's EPIC-II™B BiCMOS process and minimizes noise coupling into shared ground planes - a critical advantage in dense backplane designs where multiple transceivers switch simultaneously.