Texas Instruments SN74LVC861ADWR

Overview

SN74LVC861ADWR 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 mixed-voltage systems. It operates from 1.65 V to 3.6 V, accepts 5.5-V inputs, delivers 6.4-ns max propagation delay at 3.3 V, and supports partial-power-down via Ioff. It enables level translation in 3.3-V/5-V interfacing applications such as memory expansion and FPGA-to-ASIC interconnects.

For engineers reviewing the SN74LVC861ADWR datasheet, SN74LVC861ADWR pinout, SN74LVC861ADWR application, or SN74LVC861ADWR equivalent, key selection criteria include bidirectional 3-state control (OEAB/OEBA), 10-channel I/O voltage tolerance up to 5.5 V, guaranteed tpd ≤6.4 ns at 3.3 V, Ioff-enabled isolation during power sequencing, and TSSOP-24 package compatibility with high-density PCB layouts.

Technical Context

The SN74LVC861ADWR implements dual independent 3-state enable logic (OEAB and OEBA) to route data either from A→B or B→A, with simultaneous high-impedance isolation when both enables are high. Its CMOS input structure supports 5.5-V tolerant inputs while powered from 1.65–3.6 V, enabling seamless interfacing between legacy 5-V logic and modern low-voltage domains.

It features Ioff circuitry that disables all outputs and blocks current backflow when VCC = 0 V, satisfying JESD78 latch-up immunity (>250 mA) and JESD22 ESD robustness (2000-V HBM). The device's VOLP <0.8 V and VOHV >2 V at 3.3 V ensure signal integrity under fast switching transients in noise-sensitive digital systems.

Key Specifications

Pinout & Package

TSSOP-24 package (PW drawing), 0.65-mm lead pitch, 4.4-mm body width, 1.2-mm max height, RoHS-compliant NIPDAU finish, MSL Level-1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit bus transceiver applications.

Compared with SN74LVC861APWR, SN74LVC861ADWR offers identical performance and footprint but with TI's standard LVC861A top-side marking; versus SN74ALVC164245DGGR, it provides simpler control architecture and smaller package for 10-bit applications, avoiding unnecessary pin count and routing complexity.

Availability

SN74LVC861ADWR is available at Aetrix Electronics and suitable for memory subsystem interfacing, FPGA-to-ASIC bridging, and industrial I/O module backplanes requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74LVC861ADWR 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 connectivity technologies, with decades of experience in high-reliability logic and interface solutions.

The SN74LVC861ADWR belongs to TI's LVC logic family, engineered for low-voltage, high-speed bidirectional bus interfacing in mixed-signal systems where voltage translation, power sequencing resilience, and noise-immune timing are critical.

FAQ

What is the maximum clock/data rate supported by the SN74LVC861ADWR?

The SN74LVC861ADWR does not operate on a clock signal-it is an asynchronous transceiver. Its 6.4-ns maximum propagation delay at 3.3 V supports reliable data transfer up to approximately 100 MHz in burst-mode bus applications, assuming proper PCB layout and termination. Timing margins must be verified using the device's published tpd, ten, and tdis values under actual VCC and load conditions. SN74LVC861ADWR performance is defined by edge-to-edge delay, not clock frequency.

Can SN74LVC861ADWR safely interface a 5-V microcontroller with a 3.3-V FPGA?

Yes. The SN74LVC861ADWR accepts 5.5-V inputs while powered from 1.65–3.6 V, making it ideal for unidirectional or bidirectional signal translation between 5-V and 3.3-V domains. Its Ioff protection prevents back-current when either side is unpowered, and its 5.5-V-tolerant inputs eliminate external clamping diodes. SN74LVC861ADWR maintains full functionality without level-shifter ICs or resistor networks in this configuration.

Is the SN74LVC861ADWR pin-compatible with other 24-pin TSSOP bus transceivers?

No-SN74LVC861ADWR has a unique 10-bit dual-OE pinout (OEAB/OEBA) and specific A/B bus assignment (pins 1–10 and 13–22) that differs from industry-standard 16-bit or octal transceivers. While the TSSOP-24 package footprint matches JEDEC MO-153, the signal mapping is not interchangeable. Replacing it requires schematic and layout revision. SN74LVC861ADWR's pinout is fixed per TI's SCAS309I datasheet.

Does SN74LVC861ADWR require external pull-up resistors on OEAB and OEBA?

Yes-TI recommends tying OEAB and OEBA to VCC through pull-up resistors during power-up/down to guarantee high-impedance state before logic initialization. The minimum resistor value depends on the driver's sink capability; typical values range from 4.7 kΩ to 10 kΩ. Leaving OE pins floating risks undefined output states and potential bus contention. This requirement applies directly to SN74LVC861ADWR in all operating conditions.

What thermal considerations apply to SN74LVC861ADWR in continuous operation?

SN74LVC861ADWR has a θJA of 88°C/W in the TSSOP-24 (PW) package. At 24-mA output drive and 3.3-V VCC, worst-case power dissipation is ~80 mW per active channel. With all 10 channels driven, total junction temperature rise is ~7°C above ambient-well within the –40°C to +85°C operating range. No heatsinking is required, but 2–3 thermal vias under the exposed pad (if present in variant) improve reliability. SN74LVC861ADWR thermal performance is validated per JEDEC JESD51-7.