Texas Instruments SN74LVT16646DGGR

Overview

SN74LVT16646DGGR from Texas Instruments is a 16-bit bus transceiver and 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 and 5-V systems. It features dual 8-bit or single 16-bit bidirectional data transfer, clocked storage on CLKAB/CLKBA rising edges, and real-time or stored-data routing via SAB/SBA select controls. Used in high-speed backplane and memory interface applications requiring bus isolation and hold functionality.

For engineers reviewing the SN74LVT16646DGGR datasheet, SN74LVT16646DGGR pinout, SN74LVT16646DGGR application, or SN74LVT16646DGGR equivalent, key selection criteria include its 150-MHz clock frequency, ±64-mA output drive at 3.3 V, bus-hold inputs eliminating external pullups, I_off/power-up 3-state for hot insertion, and TSSOP-56 package compatibility with dense PCB layouts.

Technical Context

The SN74LVT16646DGGR implements a flowthrough architecture with distributed V_CC/GND pins to minimize switching noise and optimize signal integrity. Its dual-register structure allows independent storage of A-bus and B-bus data on separate clock edges (CLKAB↑ stores A→B; CLKBA↑ stores B→A), enabling four distinct bus-management functions: real-time transfer, stored-data transfer, simultaneous storage, and isolation mode.

Control logic includes active-low OE for 3-state output enable/disable, DIR to determine data direction (A→B when DIR=H, B→A when DIR=L), and glitch-free SAB/SBA multiplexing that selects between transparent (real-time) and latched (stored) data paths without decoding hazards. Bus-hold circuitry maintains valid logic states on undriven A/B port inputs without external resistors.

Key Specifications

Pinout & Package

TSSOP-56 (DGG) package with 56 terminals, 12.5 mm × 6.1 mm body size, 0.5-mm lead pitch, and exposed thermal pad (not electrically connected). Pin layout optimized for flowthrough signal routing and minimized crosstalk via alternating V_CC/GND placement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVT16646DGGR, SN74LVT16245DGGR offers simpler operation but no clocked storage or select multiplexing, while SN74ALVCH16646GR provides broader low-voltage support at the cost of 5-V interface capability - making SN74LVT16646DGGR uniquely suited for mixed 3.3-V/5-V synchronous bus bridging with integrated register functionality.

Availability

SN74LVT16646DGGR is available at Aetrix Electronics and suitable for backplane interface, memory subsystem bridge, hot-swappable module, and industrial control backplane applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74LVT16646DGGR 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 over 90 years of innovation in high-reliability electronic components.

The SN74LVT16646DGGR belongs to TI's Widebus™ family of advanced BiCMOS bus interface devices, engineered specifically for high-speed, mixed-voltage system interconnect in computing, communications, and industrial equipment.

FAQ

What voltage levels does the SN74LVT16646DGGR support on its I/O ports?

The SN74LVT16646DGGR supports 5-V tolerant inputs and outputs while operating from a 3.3-V V_CC supply (2.7 V to 3.6 V). Input voltage range is −0.5 V to 7 V, allowing direct connection to 5-V TTL logic without level-shifting circuitry. This mixed-mode capability is confirmed in the "Recommended Operating Conditions" and "Electrical Characteristics" tables of the SCBS149D datasheet.

Does the SN74LVT16646DGGR require external pullup resistors on its A/B bus inputs?

No, the SN74LVT16646DGGR does not require external pullup resistors on its A/B bus inputs due to integrated bus-hold circuitry, which actively maintains valid logic states on undriven or floating inputs. The datasheet explicitly states that use of external pullup/pulldown resistors with bus-hold is not recommended, as it may interfere with the internal hold current (±75 µA at V_CC = 3 V).

How does the SN74LVT16646DGGR support hot-insertion in modular systems?

The SN74LVT16646DGGR supports hot-insertion via two complementary features: I_off circuitry disables outputs and prevents damaging current backflow when V_CC = 0, and power-up 3-state ensures outputs remain in high-impedance during power ramp-up/down. These functions are validated per JEDEC standards and documented in the "Features" and "Absolute Maximum Ratings" sections of the SCBS149D datasheet.

What is the maximum clock frequency supported by the SN74LVT16646DGGR?

The SN74LVT16646DGGR supports a maximum clock frequency of 150 MHz under recommended operating conditions (V_CC = 3.3 V ± 0.3 V, T_A = −40°C to 85°C). This value is specified in the "Timing Requirements" table of the SCBS149D datasheet and applies to both CLKAB and CLKBA inputs for reliable register clocking and data capture.

Can the SN74LVT16646DGGR operate in isolation mode with data stored independently on both buses?

Yes, the SN74LVT16646DGGR can operate in isolation mode (OE = high) while storing data independently on both A and B buses. When OE is high, outputs are disabled, but input functions remain active - allowing A-port data to be stored in the B-register and/or B-port data to be stored in the A-register on respective clock edges. This behavior is defined in the "Function Table" and "Description" sections of the SCBS149D datasheet.