Texas Instruments SN74LVT16646DL

Overview

SN74LVT16646DL from Texas Instruments is a 16-bit bus transceiver and dual-register IC designed for 3.3-V V_CC operation with 5-V tolerant inputs/outputs, supporting mixed-mode signal interfacing between 3.3-V logic and legacy 5-V systems. It features dual 8-bit clocked registers (CLKAB/CLKBA), independent direction control (DIR), output enable (OE), and select controls (SAB/SBA) enabling real-time or stored data routing. Used in high-speed backplane and motherboard bus isolation, memory interface bridging, and FPGA-to-ASIC data path management.

For engineers reviewing the SN74LVT16646DL datasheet, SN74LVT16646DL pinout, SN74LVT16646DL application, or SN74LVT16646DL equivalent, key selection criteria include its 150-MHz clock frequency support, bus-hold input circuitry eliminating external pullups, I_off/power-up 3-state for hot insertion, distributed V_CC/GND pinning for noise reduction, and dual-bus storage capability with glitch-free multiplexing.

Technical Context

The SN74LVT16646DL implements a flowthrough architecture with two independent 8-bit register banks (A/B), each controlled by dedicated clock (CLKAB/CLKBA), direction (DIR), and select (SAB/SBA) inputs. Its ABT BiCMOS process enables 3.3-V core operation while tolerating 5-V signals on A/B ports - critical for voltage-level translation without level shifters.

It supports four distinct bus-management modes: real-time bidirectional transfer (OE low + DIR controlling direction), stored-data transfer (OE low + SAB/SBA selecting register source), simultaneous A/B storage (OE high + clocks active), and isolation with hold (OE high + clocks inactive). Bus-hold circuitry maintains valid logic states on undriven inputs, and I_off protection prevents backflow during power-down.

Key Specifications

Pinout & Package

SN74LVT16646DL uses a 56-pin SSOP (Shrink Small Outline Package) with 0.635-mm lead pitch, optimized for high-density PCB layouts and thermal dissipation (θ_JA = 56°C/W). Pin numbering follows standard top-view orientation with pin 1 marked by a dot or beveled corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit bus transceiver and register applications.

Compared with SN74LVTH16646DL and SN74ALVCH16646GR, the SN74LVT16646DL uniquely combines 5-V input tolerance, bus-hold, I_off-enabled hot insertion, and 150-MHz operation in an SSOP package - making it the only option among the three qualified for mixed-voltage backplane and field-replaceable module applications.

Availability

SN74LVT16646DL is available at Aetrix Electronics and suitable for PCI-X bridge interfaces, FPGA-to-ASIC data path bridging, and industrial PLC backplane isolation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SN74LVT16646DL 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 heritage in high-reliability interface and bus technology.

The SN74LVT16646DL belongs to TI's Widebus™ family of advanced bus-interface devices, engineered specifically for voltage-domain bridging, high-speed backplane communication, and robust hot-plug-capable system architectures.

FAQ

What voltage levels does the SN74LVT16646DL support on its A/B bus pins?

The SN74LVT16646DL supports input voltages from −0.5 V to 7 V on all A and B port pins, enabling direct interfacing with 5-V TTL systems while operating from a 3.3-V supply. Its outputs swing rail-to-rail between GND and V_CC (2.7–3.6 V), and the device maintains full functionality across this entire V_CC range without level-shifting components.

How does the SN74LVT16646DL handle undriven or floating inputs?

The SN74LVT16646DL incorporates active bus-hold circuitry on all A and B port inputs, which sources or sinks ±75 µA to retain the last-valid logic state without external resistors. This feature eliminates the need for pullup/pulldown networks, reduces BOM count, and prevents undefined logic states during signal transitions or module disconnection - a key requirement in hot-swap and modular system designs.

Can the SN74LVT16646DL be used in hot-insertion applications?

Yes, the SN74LVT16646DL is fully specified for hot-insertion use via dual protection mechanisms: I_off circuitry disables outputs and blocks reverse current flow when V_CC = 0 V, and power-up 3-state forces outputs into high-impedance during power ramp-up/down. These features prevent bus contention and driver damage during live board replacement - validated per JEDEC standards for telecom and enterprise infrastructure applications.

What is the maximum clock frequency supported by the SN74LVT16646DL?

The SN74LVT16646DL supports a maximum clock frequency of 150 MHz across its recommended operating conditions (V_CC = 2.7 V to 3.6 V, T_A = −40°C to 85°C). This is confirmed by timing specifications including t_w (minimum pulse width ≥3.3 ns) and f_max (150 MHz) in the official datasheet SCBS149D, ensuring reliable register capture and propagation at industry-standard high-speed bus rates.

Does the SN74LVT16646DL require external pullup resistors on its control inputs?

No, the SN74LVT16646DL does not require external pullup resistors on DIR, OE, CLK, or SAB/SBA inputs because all control inputs have defined VIH/VIL thresholds (VIH = 2.0 V, VIL = 0.8 V) and internal biasing compatible with standard 3.3-V CMOS logic. However, TI recommends tying unused control inputs directly to V_CC or GND to ensure deterministic operation and avoid noise-induced glitches - per Application Report SCBA004.