Texas Instruments SN74ABT657ADBR

Overview

SN74ABT657ADBR from Texas Instruments is an octal transceiver with integrated parity generator/checker and 3-state outputs in a 24-pin SSOP package. It supports bidirectional data flow (A↔B), real-time odd/even parity generation and checking, and delivers high-drive outputs (–32 mA IOH, 64 mA IOL) for robust bus interfacing in industrial control backplanes.

For engineers reviewing the SN74ABT657ADBR datasheet, SN74ABT657ADBR pinout, SN74ABT657ADBR application, or SN74ABT657ADBR equivalent, key selection criteria include its 5-V operation, 4.3 ns typical propagation delay (A→B), ±10 µA high-impedance leakage, and flow-through pinout optimized for PCB layout in memory-mapped I/O systems.

Technical Context

This BiCMOS transceiver implements noninverting bidirectional buffering with dedicated parity logic: ODD/EVEN selects parity sense, PARITY serves as output (transmit) or input (receive), and ERR asserts low on parity mismatch. Direction is controlled by T/R; 3-state enable/disable is managed by OE.

It features EPIC-II™B process technology enabling low power dissipation, high-impedance state during power-up/down (VCC < 2.1 V), and latch-up immunity >500 mA per JESD-17. Output ground bounce (VOLP) remains <1 V at 5 V/25°C.

Key Specifications

Pinout & Package

SN74ABT657ADBR uses a 24-pin Shrink Small-Outline Package (SSOP, DB package code), 0.64 mm pitch, body width 5.3 mm, footprint compatible with JEDEC MO-153.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ABT657ADBR, SN74ABT245DBR removes parity functionality but retains pin compatibility and drive performance, while 74ACT16652DLR expands data width and parity capability at the cost of package size and power. SN74ABT657ADBR uniquely balances 8-bit width, hardware parity, and compact SSOP packaging for industrial bus nodes.

Availability

SN74ABT657ADBR is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory-mapped I/O expansion, legacy bus arbitration systems, and diagnostic data acquisition hubs requiring stable component supply and long-term lifecycle support.

Supply support for SN74ABT657ADBR 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 for industrial, automotive, and communications markets.

The ABT logic family-including SN74ABT657ADBR-is designed for high-speed, low-power 5-V TTL-compatible bus interfacing with enhanced noise immunity and robust ESD protection.

FAQ

What is the function of the ODD/EVEN pin on the SN74ABT657ADBR?

The ODD/EVEN pin on the SN74ABT657ADBR selects the parity mode: logic high configures odd parity, logic low configures even parity. During transmit mode, this setting determines whether the PARITY output is driven high or low to ensure the total number of high bits across A1–A8 plus PARITY matches the selected sense. In receive mode, it defines the expected parity for ERR assertion.

Does the SN74ABT657ADBR support hot insertion or live bus swapping?

Yes, the SN74ABT657ADBR supports controlled hot insertion: its high-impedance state activates automatically when VCC drops below 2.1 V during power-up/down, and OE can be held high externally to force tri-state before power application. However, external current-limiting resistors on A/B lines are recommended to prevent inrush current damage during live insertion.

Can the SN74ABT657ADBR operate at 3.3 V?

No, the SN74ABT657ADBR is specified only for 4.5 V to 5.5 V operation per its recommended operating conditions. At 3.3 V, VIH and VOL thresholds are not guaranteed, and output drive strength degrades significantly. For 3.3-V systems, consider TI's LVC or AUC series transceivers with native 3.3-V compatibility.

How does the ERR output behave during receive mode on the SN74ABT657ADBR?

In receive mode (T/R low), the ERR output on the SN74ABT657ADBR goes low when the number of high bits on B1–B8 plus the PARITY input does not match the parity sense set by ODD/EVEN. For example, with ODD/EVEN high (odd parity) and PARITY high, ERR is low if B-bus has an even count of high bits-indicating a detected error. ERR remains high when parity is correct.

Is the SN74ABT657ADBR pin-compatible with the SN74ABT657ADW?

Yes, the SN74ABT657ADBR (SSOP-24) and SN74ABT657ADW (SOIC-24) share identical pin numbering, signal assignment, and electrical specifications. Both use the same DW package drawing variant per TI documentation, enabling drop-in replacement on PCBs where package height or thermal profile permits SSOP-to-SOIC substitution.