Texas Instruments SN74ABT651DBLE

Overview

SN74ABT651DBLE from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, designed for bidirectional data multiplexing between two 8-bit buses (A and B). It integrates D-type flip-flops, dual clock inputs (CLKAB/CLKBA), dual select controls (SAB/SBA), and independent output enables (OEAB/OEBA), supporting real-time or stored data transfer at up to 125 MHz with ±32-mA high-drive outputs.

For engineers reviewing the SN74ABT651DBLE datasheet, SN74ABT651DBLE pinout, SN74ABT651DBLE application, or SN74ABT651DBLE equivalent, key selection criteria include its dual-register storage capability, 5-V operation with TTL-compatible thresholds, latch-up immunity (>500 mA), ESD protection (>2000 V HBM), and support for isolated bus hold via OE control during power sequencing.

Technical Context

The SN74ABT651DBLE implements a BiCMOS EPIC-II^B architecture enabling low-power, high-speed bus management. Its dual-clock domain allows independent latching of A- and B-bus data on rising edges of CLKAB and CLKBA, while SAB/SBA determine whether transceivers pass real-time or registered data.

Output-enable logic ensures robust power-up/down behavior: OEBA tied to VCC via pullup and OEAB to GND via pulldown guarantees high-impedance states before internal logic stabilizes. The device supports simultaneous real-time reinforcement (OEAB+OEBA low) and selective storage without register use - critical for glitch-free bus arbitration in industrial backplanes.

Key Specifications

Pinout & Package

SN74ABT651DBLE is packaged in a 24-pin Shrink Small-Outline (DB) package with 300-mil body width and 0.65-mm lead pitch, optimized for high-density PCB layouts in space-constrained embedded systems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ABT651DBLE, SN74ABT245DW omits register functionality entirely, trading storage flexibility for lower cost and pin count, while SN74LVTH16245DGGR shifts to 3.3-V operation with faster timing but weaker drive - making SN74ABT651DBLE the sole choice for 5-V systems requiring integrated latching and high-current bus driving.

Availability

SN74ABT651DBLE is available at Aetrix Electronics and suitable for industrial PLC backplanes, automated test equipment, legacy bus extenders, and embedded memory bridges requiring stable component supply and long-term lifecycle support.

Supply support for SN74ABT651DBLE 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 industrial and automotive components.

The ABT logic family - including SN74ABT651DBLE - was engineered for robust 5-V bus interfacing in noise-prone industrial environments, emphasizing latch-up immunity, ESD resilience, and deterministic timing under varying load conditions.

FAQ

What is the primary function of the SN74ABT651DBLE in a system?

The SN74ABT651DBLE serves as an octal bidirectional bus transceiver with integrated D-type flip-flop registers, enabling both real-time data transfer and synchronized storage between two 8-bit buses. Its dual-clock and dual-select architecture allows flexible bus management - such as isolating buses, latching data from either side, or forwarding stored values - making it ideal for industrial control backplanes and test equipment interfaces where timing determinism and bus integrity are critical. The SN74ABT651DBLE operates at 5 V with TTL-compatible thresholds and delivers ±32-mA/±64-mA drive strength.

Does the SN74ABT651DBLE support hot-swap or power sequencing safety?

Yes - the SN74ABT651DBLE includes design provisions for safe power-up and power-down. TI recommends tying OEBA to VCC via a pullup resistor and OEAB to GND via a pulldown resistor to guarantee high-impedance outputs before internal logic stabilizes. This prevents bus contention during voltage ramping, a key requirement in modular systems like PLC racks or hot-pluggable test modules. The SN74ABT651DBLE's latch-up immunity (>500 mA per JESD17) and ESD protection (>2000 V HBM) further enhance robustness during field servicing.

Can the SN74ABT651DBLE operate at frequencies above 100 MHz?

Yes - the SN74ABT651DBLE is characterized for operation up to 125 MHz clock frequency at VCC = 5 V and TA = 25°C, with propagation delays as low as 1.5 ns (typical) for A↔B data paths. Its EPIC-II^B BiCMOS process delivers consistent timing across temperature and voltage ranges, supporting high-speed data acquisition and real-time control loops. For sustained 125-MHz operation, proper PCB layout (controlled impedance, minimized stubs, local decoupling) and load capacitance ≤50 pF (per datasheet test condition) are required. The SN74ABT651DBLE maintains full specification compliance within its –40°C to +85°C operating range.

How does the SN74ABT651DBLE handle simultaneous data storage on both buses?

The SN74ABT651DBLE supports concurrent latching of A- and B-bus data via independent rising-edge-triggered clocks: CLKAB latches A1–A8 into the A register, and CLKBA latches B1–B8 into the B register. When both clocks receive synchronous rising edges, data from both buses is captured simultaneously - enabling atomic snapshot operations essential for coherent system state capture in diagnostics or fault logging. The SN74ABT651DBLE's function table confirms this behavior under "Store A and B data" (OEAB=low, OEBA=high, CLKAB↑, CLKBA↑), with no dependency on SAB/SBA state during the latch event.

Is the SN74ABT651DBLE pin-compatible with other ABT-series transceivers?

No - the SN74ABT651DBLE has a unique 24-pin DB package pinout optimized for its dual-register, dual-clock, dual-select architecture. Unlike simpler transceivers (e.g., SN74ABT245), it dedicates pins to CLKAB, CLKBA, SAB, SBA, and separate OEAB/OEBA controls - resulting in non-interchangeable pin mapping. Substituting with another ABT device requires PCB redesign. The SN74ABT651DBLE's pin configuration is documented in Figure 1 and the logic diagram of the SCBS083E datasheet, confirming its distinct terminal assignment for multiplexed bus management.