Texas Instruments SN74LVTH646DGVR

Overview

SN74LVTH646DGVR from Texas Instruments is a 3.3-V octal bus transceiver with registers, dual-clock control (CLKAB/CLKBA), direction control (DIR), and output enable (OE), supporting mixed-mode 5-V/3.3-V interfacing in high-speed data paths. It features bus-hold on all A/B data inputs, Ioff for hot insertion, and operates down to 2.7 V supply. Used in backplane interface logic and voltage-level translation between legacy 5-V and modern 3.3-V subsystems.

For engineers reviewing the SN74LVTH646DGVR datasheet, SN74LVTH646DGVR pinout, SN74LVTH646DGVR application, or SN74LVTH646DGVR equivalent, key selection considerations include its 24-pin TVSOP package, 150-MHz clock frequency support, bus-hold input retention, hot-insertion capability via Ioff and power-up 3-state, and dual-register storage architecture enabling time-multiplexed A↔B data routing.

Technical Context

The SN74LVTH646DGVR integrates eight bidirectional data channels, each with independent D-type flip-flop registers clocked on low-to-high transitions of CLKAB (A→B) or CLKBA (B→A). Control logic enables real-time or stored-data transfer via DIR, OE, SAB, and SBA signals - allowing isolation, transparent pass-through, or registered multiplexing modes.

It implements active bus-hold circuitry on all A1–A8 and B1–B8 inputs (±75 µA hold current at VCC = 3 V), eliminating external pull resistors. Ioff protection disables outputs when VCC = 0 V (±100 µA leakage), and power-up 3-state ensures high-impedance during power sequencing - critical for live insertion in modular systems.

Key Specifications

Pinout & Package

SN74LVTH646DGVR is housed in a 24-pin Thin Very Small Outline Package (TVSOP), 4.4 mm × 5.0 mm body, 0.65 mm lead pitch, 1.2 mm max height, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC646APW, SN74LVTH646DGVR delivers guaranteed hot-swap safety and input retention without external components; compared with SN74ALVCH16646DL, it offers optimal size and power for 8-bit space-constrained applications where 16-bit width is unnecessary.

Availability

SN74LVTH646DGVR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system upgrades, and modular computing chassis requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for SN74LVTH646DGVR 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 LVTH logic family - including SN74LVTH646DGVR - was engineered for robust mixed-voltage system integration, targeting telecom infrastructure, industrial automation, and test equipment where voltage translation, hot-swap resilience, and deterministic timing are critical.

FAQ

What is the maximum clock frequency supported by the SN74LVTH646DGVR?

The SN74LVTH646DGVR supports a maximum clock frequency of 150 MHz under recommended operating conditions (VCC = 3.3 V ± 0.3 V). This rating applies to both CLKAB and CLKBA inputs and is validated with CL = 50 pF loads. Timing margins decrease below 3.0 V VCC, so operation at 150 MHz requires stable 3.3-V supply regulation.

Does the SN74LVTH646DGVR require external pullup or pulldown resistors on its A/B data lines?

No, the SN74LVTH646DGVR does not require external pullup or pulldown resistors on A1–A8 or B1–B8 inputs because it integrates active bus-hold circuitry. This feature maintains valid logic states on unused or floating inputs with ±75 µA hold current at VCC = 3 V. Adding external resistors may interfere with bus-hold operation and is explicitly discouraged in the datasheet.

Can the SN74LVTH646DGVR be used in hot-insertion applications?

Yes, the SN74LVTH646DGVR is fully specified for hot-insertion applications. Its Ioff circuitry disables outputs when VCC = 0 V (±100 µA leakage), preventing damaging current backflow. Combined with power-up 3-state logic, it ensures outputs remain high-impedance during power ramp-up/down - a requirement verified per JESD78 and applied in telecom line cards and modular servers.

What is the function of the NC pins on the SN74LVTH646DGVR?

The SN74LVTH646DGVR has four NC (No Connection) pins: pins 11, 12, 20, and 23. These pins have no internal connection and must remain unconnected on the PCB. They are reserved for package mechanical integrity or future device variants - routing traces or placing vias on them violates TI's layout guidelines and may compromise thermal or electrical performance.

How does the SN74LVTH646DGVR handle 5-V input signals while operating at 3.3-V VCC?

The SN74LVTH646DGVR accepts 5-V input signals (up to 5.5 V) on all A/B data and control inputs while powered from a 3.3-V VCC supply. Its input structure includes clamping diodes and robust ESD protection (2000-V HBM), enabling direct interfacing with 5-V TTL buses without external level shifters - a core design feature confirmed in the absolute maximum ratings and recommended operating conditions tables.