Texas Instruments SN74LVC861ADW

Overview

SN74LVC861ADW from Texas Instruments is a 10-bit bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in 1.65-V to 3.6-V systems. It features dual output-enable controls (OEAB/OEBA), supports mixed-mode 3.3-V/5-V I/O, and delivers 6.4 ns max propagation delay at 3.3 V - enabling use in level-shifting interfaces for industrial control backplanes and FPGA-to-ASIC interconnects.

For engineers reviewing the SN74LVC861ADW datasheet, SN74LVC861ADW pinout, SN74LVC861ADW application, or SN74LVC861ADW equivalent, key selection considerations include its Ioff partial-power-down capability, 5.5-V-tolerant inputs, ±24-mA drive strength at 3 V, and SOIC-24 package compatibility with legacy board layouts requiring robust bus isolation.

Technical Context

The SN74LVC861ADW implements independent directional control via separate OEAB (A→B enable) and OEBA (B→A enable) inputs, allowing simultaneous isolation or latched bidirectional operation per the function table. Its LVC logic family ensures TTL-compatible thresholds across 1.65–3.6 V VCC while maintaining 5.5-V input tolerance.

Internal Ioff circuitry actively disables outputs during power-down, blocking reverse current flow - critical for hot-swap and multi-rail systems. Output ground bounce (VOLP < 0.8 V) and undershoot (VOHV > 2 V) are characterized at 3.3 V/25°C, confirming signal integrity in high-speed digital backplanes.

Key Specifications

Pinout & Package

SN74LVC861ADW uses a 24-pin SOIC (DW) package with 300-mil body width, 1.27-mm lead pitch, and JEDEC MO-153-compliant outline. Pin 1 is located at the top-left corner adjacent to the index notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC861APW, the SN74LVC861ADW offers identical functionality in a wider SOIC package suited for manual prototyping and legacy rework; versus SN74ALVC164245DGGR, it provides simpler OE-based control at half the channel count and lower cost, but lacks dual-supply flexibility.

Availability

SN74LVC861ADW is available at Aetrix Electronics and suitable for industrial backplane interfaces, FPGA-to-microcontroller bridges, hot-swappable module adapters, and legacy system upgrade interfaces requiring stable component supply and long-term manufacturability.

Supply support for SN74LVC861ADW 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 expertise in high-reliability interface ICs.

The SN74LVC861ADW belongs to TI's LVC logic family - engineered for low-voltage operation, mixed-signal compatibility, and robust performance in industrial and communications infrastructure applications.

FAQ

What is the recommended power-up sequence for SN74LVC861ADW to avoid bus contention?

TI specifies that OEAB and OEBA must be held high (via pull-up resistors to VCC) during power-up to guarantee high-impedance outputs. For SN74LVC861ADW, use ≥10-kΩ resistors tied to the same VCC rail; this prevents unintended data leakage before system initialization completes. The device does not require strict VCC ramp ordering relative to other rails due to its 5.5-V-tolerant inputs.

Can SN74LVC861ADW operate reliably at 1.65 V VCC with 5-V inputs?

Yes - SN74LVC861ADW is fully specified down to 1.65 V VCC and accepts input voltages up to 5.5 V regardless of supply level. At 1.65 V, VIH is guaranteed ≥1.07 V (0.65×VCC), ensuring clean recognition of 5-V logic-high signals. Output VOH remains ≥1.45 V under 4-mA load, sufficient for driving downstream 1.8-V receivers.

Does SN74LVC861ADW support hot-plug operation in partially powered systems?

Yes - SN74LVC861ADW incorporates Ioff circuitry that disables outputs when VCC = 0 V, limiting reverse current to ±10 µA even with 5.5-V signals applied. This protects upstream drivers and prevents latch-up in live-backplane scenarios. No external protection components are required beyond standard decoupling.

What is the maximum clock rate supported by SN74LVC861ADW in a synchronous bus configuration?

While SN74LVC861ADW is asynchronous, its 6.4-ns max tpd at 3.3 V supports effective data rates exceeding 100 MHz in burst-mode operation. For sustained toggling, limit frequency to ≤80 MHz to accommodate setup/hold margins and PCB trace delays. The 10-bit width allows 10-byte parallel transfers per cycle, delivering up to 800 MB/s theoretical bandwidth.

How does SN74LVC861ADW handle simultaneous assertion of OEAB and OEBA?

When both OEAB and OEBA are low (L/L), the SN74LVC861ADW enters "latch" mode: A-bus and B-bus data are mirrored (A = B), effectively creating a transparent latch. This behavior is documented in the function table and enables simple bus-hold or echo functions without external feedback paths - a unique capability among LVC transceivers.