Texas Instruments SN74ABT651DBR

Overview

SN74ABT651 from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, designed for bidirectional data routing between two 8-bit buses (A and B) with real-time or registered transfer modes. It features dual clock inputs (CLKAB/CLKBA), dual select controls (SAB/SBA), dual output enables (OEAB/OEBA), high-drive capability (–32 mA IOH / 64 mA IOL), and operates at 5 V over –40°C to 85°C.

For engineers reviewing the SN74ABT651 datasheet, SN74ABT651 pinout, SN74ABT651 application, or SN74ABT651 equivalent, this device supports multiplexed bus management in memory interfaces, backplane data paths, and programmable logic interconnects where simultaneous storage and real-time transfer are required.

Technical Context

The SN74ABT651 integrates eight independent D-type flip-flops per bus direction, enabling synchronous latching of A- or B-bus data on rising clock edges. Its dual-select architecture allows independent control of data source (real-time vs. stored) for each direction via SAB and SBA pins.

Output-enable logic decouples bus drivers from signal integrity concerns: OEAB gates A→B transmission while OEBA gates B→A, both supporting high-impedance states critical for shared-bus arbitration. The EPIC-II^B BiCMOS process delivers low ground bounce (<1 V VOLP) and ESD robustness (>2 kV HBM).

Key Specifications

Pinout & Package

SN74ABT651 is packaged in a 24-pin Shrink Small-Outline (DB) package, measuring 7.5 mm × 4.4 mm × 1.75 mm, with 0.65 mm lead pitch and gull-wing leads compatible with standard surface-mount reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ABT245DW and SN74ACT573N, the SN74ABT651 uniquely integrates dual-directional registered transfer in a single 24-pin package - eliminating discrete latch + transceiver combinations and reducing PCB layout complexity for synchronous bus-multiplexing applications.

Availability

SN74ABT651 is available at Aetrix Electronics and suitable for memory interface buffering, programmable logic interconnect, and industrial control bus arbitration requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74ABT651 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 innovation in high-speed interface and bus management ICs.

The ABT logic family, including SN74ABT651, was engineered for industrial and communications systems demanding robust 5-V operation, high noise immunity, and reliable bus arbitration - targeting applications where signal integrity and timing determinism are critical.

FAQ

What is the primary function of the SN74ABT651 in a system architecture?

The SN74ABT651 serves as an octal bidirectional bus transceiver with integrated D-type registers, enabling either real-time data transfer or clocked storage and retrieval between two 8-bit buses (A and B). Its dual-clock (CLKAB/CLKBA) and dual-select (SAB/SBA) architecture allows independent control of data source per direction, making it ideal for memory interfaces and programmable logic interconnects where deterministic latency and bus isolation are required.

How does the SN74ABT651 handle power-up and power-down sequencing to avoid bus contention?

The SN74ABT651 requires OEBA to be tied to VCC through a pullup resistor and OEAB to GND through a pulldown resistor to ensure high-impedance outputs during power transitions. This prevents unintended driving of shared bus lines before system control logic initializes, mitigating contention risks in multi-master environments. Resistor values must respect the driver's current-sinking (B→A) and current-sourcing (A→B) capabilities as specified in the datasheet.

Can the SN74ABT651 operate reliably at 125 MHz, and what conditions apply?

Yes, the SN74ABT651 is rated for a maximum clock frequency of 125 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = –40°C to +85°C). This rating applies to both CLKAB and CLKBA inputs when driving CL = 50 pF loads. Achieving full-speed operation requires clean power delivery, controlled impedance PCB routing, and adherence to setup/hold times (tsu = 3 ns, th = 0 ns) relative to clock edges.

What is the significance of the EPIC-II^B BiCMOS process used in the SN74ABT651?

The EPIC-II^B BiCMOS process combines bipolar speed with CMOS low-power characteristics, delivering high-output drive (–32 mA / +64 mA), low ground bounce (<1 V VOLP), and strong ESD immunity (>2000 V HBM). This technology enables the SN74ABT651 to drive heavy capacitive loads while maintaining signal integrity in electrically noisy industrial and communications environments.

Does the SN74ABT651 support hot-swap or live-insertion in backplane applications?

The SN74ABT651 supports controlled hot-swap behavior when OEBA and OEAB are externally biased via pullup/pulldown resistors, ensuring outputs remain in high-impedance state until system power and control logic stabilize. Its latch-up immunity (>500 mA) and absolute maximum ratings (e.g., VI up to 7 V) further enhance robustness during insertion into powered backplanes - though full hot-swap compliance requires additional system-level protection circuitry.