Texas Instruments SN74ABT623DW

Overview

SN74ABT623DW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data communication between A and B buses in industrial and embedded systems. It features dual output-enable inputs (OEAB/OEBA), high-drive capability (–32 mA IOH / 64 mA IOL), operates at 4.5–5.5 V, and is rated for –40°C to 85°C.

For engineers reviewing the SN74ABT623DW datasheet, SN74ABT623DW pinout, SN74ABT623DW application, or SN74ABT623DW equivalent, this device supports isolated bus control, data direction switching, and latch-back storage mode - critical for memory expansion, peripheral interfacing, and backplane buffering in 5-V TTL-compatible systems.

Technical Context

The SN74ABT623DW implements a dual-enable logic architecture enabling four distinct operational modes: A→B transmission, B→A transmission, full isolation, and simultaneous enable (latch-back) mode where both buses retain last states. Its EPIC-II^B BiCMOS process delivers low ground bounce (<1 V VOLP) and ESD robustness (>2000 V HBM).

It supports true bidirectional data flow without internal inversion, with propagation delays as low as 1 ns (tPLH/tPHL, VCC = 5 V, TA = 25°C) and enable/disable times under 7.5 ns. Input transition rate tolerance is 5 ns/V, ensuring reliable operation with fast-edge signals in noise-sensitive environments.

Key Specifications

Pinout & Package

SN74ABT623DW is housed in a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm lead pitch, 2.65 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 octal bus transceiver applications.

Compared with SN74ABT245DW and 74ACT245SCX, the SN74ABT623DW uniquely supports dual-enable latching and higher sink current, making it optimal for industrial bus isolation and memory expansion where signal integrity and state retention are critical.

Availability

SN74ABT623DW is available at Aetrix Electronics and suitable for industrial control systems, embedded memory expansion, and peripheral bus isolation requiring stable component supply and long-term manufacturability.

Supply support for SN74ABT623DW 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 high-reliability logic families.

The SN74ABT623DW belongs to TI's ABT-series advanced bi-directional transceivers, engineered for robust 5-V TTL interoperability, low-noise operation, and industrial temperature resilience.

FAQ

What is the recommended power-up sequence for SN74ABT623DW to ensure high-impedance outputs?

TI specifies that OEBA must be tied to VCC through a pullup resistor and OEAB to GND through a pulldown resistor to guarantee high-impedance outputs during power-up and power-down. The minimum resistor values depend on driver current-sourcing/sinking capability - typical values range from 4.7 kΩ to 10 kΩ. This configuration prevents bus contention before system initialization completes. The SN74ABT623DW remains safe under these conditions across its full –40°C to 85°C operating range.

Can SN74ABT623DW operate reliably with 3.3-V input signals while powered at 5 V?

Yes - the SN74ABT623DW accepts 3.3-V logic inputs at its control (OEAB/OEBA) and data (A/B) pins when VCC = 5 V, as its VIH threshold is 2.0 V (min) and VIL is 0.8 V (max). However, outputs remain 5-V TTL levels, so interfacing to 3.3-V receivers requires external level translation or compatible 5-V-tolerant inputs. The SN74ABT623DW itself does not perform voltage translation.

Does SN74ABT623DW support hot-swap operation on live buses?

The SN74ABT623DW incorporates robust ESD protection (>2000 V HBM) and latch-up immunity (>500 mA), supporting controlled hot-swap in systems with proper current-limiting and sequencing. However, TI does not guarantee fault-free hot-insertion without additional circuitry (e.g., series resistors, slew-rate limiting). For guaranteed hot-swap compliance, dedicated hot-swap controllers should accompany the SN74ABT623DW in mission-critical applications.

What is the maximum capacitive load the SN74ABT623DW can drive while maintaining specified timing?

TI characterizes switching performance at CL = 50 pF. While the SN74ABT623DW can drive heavier loads due to its +64 mA IOL, propagation delay increases linearly with capacitance - e.g., tPHL rises ~0.5 ns per 10 pF beyond 50 pF. For designs exceeding 100 pF total load (including trace and receiver capacitance), timing margins must be re-verified using the device's output impedance model and actual layout. The SN74ABT623DW remains functional but timing-critical paths require simulation or measurement.

How does the latch-back mode work in SN74ABT623DW, and when is it useful?

When both OEAB and OEBA are logic low, the SN74ABT623DW enters latch-back mode: each output reinforces its corresponding input, holding both A and B buses in their last driven states even if all upstream drivers go high-Z. This mode is valuable in memory-mapped I/O systems where bus state must persist during CPU interrupt servicing or DMA pauses. The SN74ABT623DW maintains this behavior without external feedback components - a key differentiator from simpler transceivers.