Texas Instruments SN74LVC861ADBR

Overview

SN74LVC861ADBR from Texas Instruments is a 10-bit bus transceiver with 3-state outputs, designed for bidirectional asynchronous 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-tolerant inputs, delivers 6.4-ns max propagation delay at 3.3 V, and supports partial-power-down via Ioff. It enables voltage translation in 3.3-V/5-V interfacing applications such as memory expansion and FPGA-to-ASIC communication.

For engineers reviewing the SN74LVC861ADBR datasheet, SN74LVC861ADBR pinout, SN74LVC861ADBR application, or SN74LVC861ADBR equivalent, key selection considerations include its dual-directional 3-state control (OEAB/OEBA), 5.5-V input tolerance, Ioff-enabled power-down isolation, ±24-mA drive strength at 3 V, and SSOP-24 package compatibility with high-density PCB layouts.

Technical Context

The SN74LVC861ADBR implements independent output-enable logic for each bus direction: OEAB enables A→B transmission, OEBA enables B→A transmission, and simultaneous high on both inputs isolates both buses. Its LVC-family CMOS process ensures rail-to-rail output swing and low dynamic power consumption across 1.65–3.6-V operation.

It features robust mixed-mode signaling: inputs tolerate up to 5.5 V regardless of VCC, enabling direct connection to 5-V TTL or CMOS sources while powered from 3.3 V or lower. The Ioff circuit actively disables outputs during power-down, blocking reverse current flow and protecting upstream drivers.

Key Specifications

Pinout & Package

SN74LVC861ADBR is housed in a 24-pin SSOP (Shrink Small-Outline Package) with 0.65-mm lead pitch, 7.9-mm body width, and 1.2-mm max height - optimized for space-constrained PCBs requiring >100k-cycle reworkability and IPC-7351-compliant land patterns.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC861APWR, the SN74LVC861ADBR offers higher board density and lower thermal resistance in SSOP form; versus 74ALVC164245DGGR, it provides simpler single-supply operation and lower gate count but lacks dual-rail translation capability - making it optimal for same-domain bus extension rather than cross-voltage bridging.

Availability

SN74LVC861ADBR is available at Aetrix Electronics and suitable for memory expansion interfaces, FPGA-to-MCU bridges, and industrial PLC backplanes requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for SN74LVC861ADBR 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 IC design.

The SN74LVC861ADBR belongs to TI's LVC logic family, engineered for low-voltage, high-speed bidirectional bus interfacing in industrial, computing, and communications systems where power efficiency and mixed-signal compatibility are critical.

FAQ

What is the maximum operating frequency supported by the SN74LVC861ADBR?

The SN74LVC861ADBR does not specify a maximum clock frequency because it is an asynchronous transceiver - its speed is governed by propagation delay and setup/hold timing. With a max tpd of 6.4 ns at 3.3 V, it supports data rates up to ~150 MHz in point-to-point configurations assuming clean edges and minimal trace skew. System-level bandwidth depends on bus loading, termination, and controller timing margins - always verify with actual layout simulation.

Can the SN74LVC861ADBR be used for unidirectional data transfer only?

Yes, the SN74LVC861ADBR supports unidirectional operation: tie OEBA high (inactive) and control data flow exclusively via OEAB for A→B transfer, or vice versa. This configuration simplifies timing in master-slave architectures and reduces control signal routing. Unused OE pin must be held static (VCC or GND) per TI SCBA004 guidelines to prevent floating-input-induced shoot-through current.

Does the SN74LVC861ADBR require external pull-up resistors on OEAB and OEBA pins?

Yes - to ensure defined high-impedance state during power-up/power-down, OEAB and OEBA must be pulled to VCC through external resistors. TI recommends ≥10-kΩ for standard CMOS drivers; value depends on driver sink strength and acceptable rise time. Leaving either OE pin floating risks undefined output states, increased ICC, and potential bus contention during reset sequences.

Is the SN74LVC861ADBR compatible with 1.8-V logic systems?

Yes - the SN74LVC861ADBR is fully specified down to VCC = 1.65 V, including VIH/VIL thresholds, drive strength, and timing. At 1.8 V, it delivers ≥4-mA output drive (IOL/IOH), supports 5.5-V-tolerant inputs, and maintains 6.8-ns max tpd. Ensure all connected devices meet 1.8-V logic thresholds and that VCC decoupling meets TI's 0.1-µF + 4.7-µF recommendation for transient current handling.

What is the thermal resistance (θJA) of the SN74LVC861ADBR in its SSOP package?

The SN74LVC861ADBR in SSOP (DB) package has a junction-to-ambient thermal resistance (θJA) of 63°C/W under standard JEDEC test conditions (1-layer 1-in² copper pad). This value assumes proper PCB layout with thermal vias and adequate copper pour. For sustained 24-mA output loading across all 20 channels, junction temperature rise remains below 40°C at 25°C ambient - well within the –40°C to +85°C operating range.