Texas Instruments SN74ABT623DWR

Overview

SN74ABT623DWR 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 controls (OEAB/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. Used in backplane interfaces and memory expansion subsystems where bus isolation and direction control are critical.

For engineers reviewing the SN74ABT623DWR datasheet, SN74ABT623DWR pinout, SN74ABT623DWR application, or SN74ABT623DWR equivalent, key selection considerations include its 20-pin SOIC (DW) package, true bidirectional data flow, 3-state output timing (tPLZ/tPHZ ≤ 7.5 ns), and compatibility with TTL-level control logic in legacy bus architectures.

Technical Context

This device implements a dual-enable transceiver architecture: OEAB enables A→B transmission, OEBA enables B→A transmission, and simultaneous assertion of both enables transparent latching mode where outputs reinforce inputs. Its EPIC-II^B BiCMOS process delivers low ground bounce (<1 V VOLP) and ESD robustness (>2000 V HBM).

Switching performance is characterized under CL = 50 pF with propagation delays as low as 1 ns (tPLH/tPHL min) and enable/disable times (tPZH/tPLZ) ranging from 1.2 to 7.5 ns. Absolute maximum ratings include 7 V supply tolerance and 128 mA sink current per output for transient surge resilience.

Key Specifications

Pinout & Package

SN74ABT623DWR uses a 20-pin SOIC (DW) package with 7.5 mm body width, 2.65 mm max height, and 1.27 mm lead pitch per JEDEC MS-013. Pin 1 is located at the top-left corner with index marking in the upper-left quadrant of the package outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ABT245DW and 74LVC245APW, SN74ABT623DWR uniquely supports dual-enable latching and 5-V operation in SOIC-20, making it irreplaceable in legacy industrial bus isolation where bus state retention during control transitions is mandatory.

Availability

SN74ABT623DWR is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory expansion subsystems, and legacy system bus extenders requiring stable component supply across extended product lifecycles.

Supply support for SN74ABT623DWR 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 50 years of industrial-grade component heritage.

The ABT logic family, including SN74ABT623DWR, was engineered for high-noise industrial environments requiring robust 5-V bus interfacing, fast edge rates, and latch-through data retention - targeting PLCs, motion controllers, and test equipment.

FAQ

What is the recommended power-up sequencing for SN74ABT623DWR to avoid bus contention?

TI recommends tying OEBA to VCC through a pullup resistor and OEAB to GND through a pulldown resistor during power-up. This ensures both output enables are inactive (high-impedance) until system logic asserts valid control states. The minimum resistor values depend on driver sourcing/sinking capability but typically fall between 4.7 kΩ and 10 kΩ. This prevents unintended data leakage or bus conflicts before firmware initializes the transceiver control lines in SN74ABT623DWR-based systems.

Does SN74ABT623DWR support hot-swap operation on live 5-V buses?

SN74ABT623DWR supports hot-swap conditions due to its absolute maximum rating of 7 V on VCC and –0.5 V to 5.5 V on outputs, combined with 128 mA per-output sink capability. However, TI does not guarantee glitch-free operation during insertion; external series resistors (e.g., 10–33 Ω) on A/B bus lines are recommended to limit inrush current and reduce contact arcing. The device's high ESD rating (>2000 V HBM) further enhances survivability in field-replaceable modules using SN74ABT623DWR.

Can SN74ABT623DWR operate reliably with 50-pF load capacitance on all 16 I/O lines simultaneously?

Yes - SN74ABT623DWR's switching characteristics (tPLH/tPHL, tPZH/tPLZ) are explicitly characterized at CL = 50 pF per output, and its 64-mA IOL drive strength ensures signal rise/fall times remain within specification even with worst-case trace + connector + stub capacitance totaling 50 pF. Layout best practices (short traces, ground plane, local decoupling) are still required, but no derating is needed for SN74ABT623DWR when operating at rated 5-V supply and ambient temperature.

What is the function of simultaneous OEAB and OEBA assertion in SN74ABT623DWR?

When both OEAB and OEBA are low, SN74ABT623DWR enters transparent latching mode: each A-port output reinforces its corresponding A-input, and each B-port output reinforces its B-input. With all external drivers in high-impedance state, this creates a self-holding loop that preserves the last valid logic state on both A and B buses - effectively storing 16 bits without external memory. This behavior is unique to SN74ABT623DWR among standard octal transceivers and is documented in its functional table.

Is SN74ABT623DWR pin-compatible with earlier SN74F623 or SN74LS623 devices?

No - SN74ABT623DWR shares the same 20-pin SOIC (DW) footprint and pinout as SN74F623 and SN74LS623, but its electrical interface differs significantly: ABT logic has higher drive, faster edges, and different input thresholds (VIH = 2 V vs. TTL's 2.0 V, but with CMOS-like input structure). While mechanical replacement is possible, direct substitution requires validation of timing margins, noise immunity, and bus loading - SN74ABT623DWR is not a drop-in upgrade without system-level verification.