Texas Instruments SN74LVC861APWT

Overview

SN74LVC861APWT 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 is used in industrial backplane interfaces requiring level translation between 3.3-V logic and legacy 5-V peripherals.

For engineers reviewing the SN74LVC861APWT datasheet, SN74LVC861APWT pinout, SN74LVC861APWT application, or SN74LVC861APWT equivalent, key selection criteria include its dual-directional OEAB/OEBA control architecture, 5.5-V input tolerance on all ports, guaranteed 3.6-V absolute maximum output voltage rating, and TVSOP-24 package compatibility with high-density PCB layouts.

Technical Context

The SN74LVC861APWT implements independent active-low output-enable controls (OEAB and OEBA) that determine data flow direction: OEAB low enables A→B transmission, OEBA low enables B→A transmission, both high isolate buses, and both low latch A = B. Its LVC logic family ensures CMOS-compatible thresholds across 1.65–3.6-V VCC while maintaining 5.5-V input tolerance through robust clamping structures.

This device uses true 3-state output drivers with controlled VOLP (<0.8 V) and VOHV (>2 V) at 3.3 V, enabling clean signal integrity in noisy industrial environments. The Ioff feature disables all outputs when VCC = 0 V, preventing backflow current during hot-insertion or partial power-down sequences - critical for modular system architectures.

Key Specifications

Pinout & Package

SN74LVC861APWT is housed in a 24-pin TVSOP (Thin Very Small Outline Package) with 0.4-mm lead pitch, 6.6-mm width, and 1.2-mm maximum height - optimized for space-constrained industrial PCBs and compatible with standard SMT reflow profiles (MSL Level-1).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC861APWR and SN74LVC861ADGVR, the SN74LVC861APWT provides identical core transceiver functionality in a TVSOP-24 package optimized for low-volume flexibility - its 250-unit tape configuration simplifies inventory management for engineering validation and pilot runs without sacrificing signal integrity or mixed-voltage capability.

Availability

SN74LVC861APWT is available at Aetrix Electronics and suitable for industrial backplane interfaces, modular PLC I/O expansion, automated test equipment fixtures, and medical data acquisition modules requiring stable component supply and long-term lifecycle support.

Supply support for SN74LVC861APWT 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 over 50 years of innovation in industrial, automotive, and communications markets.

The SN74LVC861APWT belongs to TI's LVC logic family, engineered for low-voltage, high-speed bidirectional bus interfacing in mixed-signal industrial systems where voltage translation, power sequencing robustness, and ESD resilience are critical.

FAQ

What is the recommended power-up sequence for SN74LVC861APWT to avoid bus contention?

TI specifies that OEAB and OEBA must be held high (inactive) during power-up to maintain all outputs in high-impedance state. Tie both pins to VCC via ≥10-kΩ pull-up resistors; this ensures no unintended data flow before system initialization completes. The SN74LVC861APWT's Ioff feature further protects against backfeed if VCC ramps after other rails. Always verify timing margins using the tdis and ten values from the switching characteristics table in the SN74LVC861APWT datasheet.

Can SN74LVC861APWT interface directly between a 3.3-V microcontroller and a 5-V ADC without external components?

Yes - the SN74LVC861APWT accepts 5.5-V inputs regardless of VCC level, so its A or B ports can safely receive 5-V logic signals while operating at 3.3-V VCC. Its outputs swing rail-to-rail (VOH ≈ VCC, VOL ≈ 0 V), making it ideal for driving 3.3-V receivers. However, to drive a 5-V ADC input, confirm the ADC's VIH requirement is ≤3.3 V; if not, an additional 3.3-V-to-5-V translator is needed downstream of the SN74LVC861APWT.

Does SN74LVC861APWT support hot-plug operation in modular systems?

Yes - the SN74LVC861APWT includes Ioff circuitry that disables outputs when VCC = 0 V, preventing damaging current backflow during insertion into a live backplane. This feature, combined with ±1000-V CDM ESD rating, makes the SN74LVC861APWT suitable for hot-plug-capable industrial modules. Ensure OEAB/OEBA are externally pulled high during insertion to guarantee high-impedance state until firmware configures direction control.

What is the thermal resistance (θJA) of the SN74LVC861APWT in its TVSOP package?

The SN74LVC861APWT in TVSOP (DGV) package has a junction-to-ambient thermal resistance (θJA) of 86°C/W, measured under standard JEDEC conditions (1-layer 1-in² copper pad). This value assumes proper PCB layout with adequate copper pour and thermal vias beneath the exposed pad (if present). For continuous 24-mA output loading across all 10 channels, junction temperature rise remains within limits up to +75°C ambient - verify with actual power dissipation using Cpd = 29 pF per transceiver from the SN74LVC861APWT datasheet.

How does the SN74LVC861APWT handle simultaneous assertion of OEAB and OEBA low?

When both OEAB and OEBA are low, the SN74LVC861APWT enters "latch" mode (A = B), where outputs mirror their respective inputs - effectively creating transparent bidirectional pass-through behavior. This is distinct from contention: internal logic prevents driver conflict by synchronizing A/B bus states. The function table in the SN74LVC861APWT datasheet confirms this behavior is intentional and electrically safe, with no increased current draw or reliability risk.