Texas Instruments SN74LVC16646ADGG

Overview

SN74LVC16646ADGG from Texas Instruments is a 16-bit bus transceiver and register with 3-state outputs, designed for mixed-voltage system interfacing between 3.3-V and 5-V logic domains. It operates from 1.65 V to 3.6 V, supports 5.5-V-tolerant inputs, delivers 5.7 ns max propagation delay at 3.3 V, and features Ioff partial-power-down protection. It enables bidirectional data flow between A and B buses with register storage, clocked on rising edges of CLKAB/CLKBA.

For engineers reviewing the SN74LVC16646ADGG datasheet, SN74LVC16646ADGG pinout, SN74LVC16646ADGG application, or SN74LVC16646ADGG equivalent, key selection criteria include its dual 8-bit or single 16-bit configurable transceiver mode, 56-pin TSSOP (DGG) package, 3.3-V–optimized timing with 5.7 ns tpd, mixed-mode voltage translation capability, and Ioff-enabled power-down isolation in partial-power-down systems.

Technical Context

The SN74LVC16646ADGG integrates two independent 8-bit transceiver/register blocks-each with D-type flip-flops, direction control (DIR), output enable (OE), and select-control (SAB/SBA) logic-enabling four bus-management functions: real-time A↔B transfer, stored-data A↔B transfer, simultaneous A/B register storage, and isolation with hold. Its architecture eliminates multiplexer decoding glitches during transitions between transparent and registered modes.

It implements true 3.3-V core operation while accepting 5-V inputs across all ports, enabling seamless level translation without external resistors. The Ioff circuitry actively disables outputs during power-down, blocking reverse current flow even when VCC = 0 V and I/O pins are driven at 5 V-critical for hot-swap and partial-power-down compliance per JESD 78.

Key Specifications

Pinout & Package

TSSOP-56 (DGG) package: 12.6 mm × 6.2 mm × 1.2 mm body, 0.5-mm pitch, lead-free, RoHS-compliant surface-mount package with exposed thermal pad (JEDEC MO-153).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC16245ADGGR and SN74ALVC164245DGGR, the SN74LVC16646ADGG uniquely combines register storage, glitch-free multiplexing, 1.65-V operation, and Ioff-making it the sole option for mixed-voltage systems requiring deterministic timing, power-down safety, and real-time/stored data arbitration.

Availability

SN74LVC16646ADGG is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive ADAS camera aggregators, PCIe-adjacent root complexes, and automated test equipment requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SN74LVC16646ADGG 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 and power management ICs.

The SN74LVC16646ADGG belongs to TI's Widebus™ family of advanced bus-interface devices, engineered specifically for high-speed, mixed-voltage board-level interconnect in industrial automation, communications infrastructure, and automotive electronics.

FAQ

What is the maximum clock frequency supported by the SN74LVC16646ADGG?

The SN74LVC16646ADGG supports a maximum clock frequency of 150 MHz at VCC = 2.7 V or 3.3 V, as specified in the timing requirements table. This applies to both CLKAB and CLKBA inputs for registering data from either bus. At lower VCC (e.g., 1.8 V), the max frequency reduces to 85 MHz. The device achieves this performance while maintaining 5.7 ns propagation delay at 3.3 V, making SN74LVC16646ADGG suitable for high-throughput synchronous bus applications.

Does the SN74LVC16646ADGG support true 5-V tolerant I/O when operating at 3.3 V?

Yes, the SN74LVC16646ADGG supports 5.5-V tolerant inputs across all A and B port pins when VCC is between 1.65 V and 3.6 V-verified per absolute maximum ratings and recommended operating conditions. Outputs swing rail-to-rail (0 V to VCC) but may be pulled to 5 V externally in 3-state mode without damage, thanks to Ioff and robust clamp structures. This makes SN74LVC16646ADGG ideal for translating between 3.3-V logic and legacy 5-V peripherals without external components.

How does the Ioff feature of the SN74LVC16646ADGG protect the system during partial power-down?

The Ioff feature in SN74LVC16646ADGG disables all outputs when VCC = 0 V, limiting leakage current to ±10 µA even if I/O pins are driven at up to 5.5 V. This prevents damaging reverse current flow from live buses into unpowered sections-a critical requirement for hot-swap, modular power architectures, and battery-backed subsystems. Unlike basic high-impedance states, Ioff is actively enforced regardless of OE or DIR state, ensuring SN74LVC16646ADGG remains safe during uncontrolled power sequencing.

Can the SN74LVC16646ADGG be used as two independent 8-bit transceivers?

Yes, the SN74LVC16646ADGG is explicitly designed to operate as two independent 8-bit transceivers. Pins 1–28 control the first 8-bit block (1A1–1A8, 1B1–1B8, 1DIR, 1OE, etc.), while pins 29–56 control the second (2A1–2A8, 2B1–2B8, 2DIR, 2OE, etc.). Each block has dedicated clocks (CLKAB/CLKBA), select controls (SAB/SBA), and direction/output enables-allowing fully autonomous operation, such as buffering separate data paths in a dual-channel interface. This dual-function capability is confirmed in the device description and function table of the SN74LVC16646ADGG datasheet.

What is the purpose of the SAB and SBA pins on the SN74LVC16646ADGG?

The SAB (Select A→B) and SBA (Select B→A) pins on SN74LVC16646ADGG control whether data transferred between buses comes from real-time inputs or from internally registered values. For example, SAB = L routes live A-bus data to B-bus outputs; SAB = H routes stored A-register data instead. Crucially, the internal logic eliminates decoding glitches during transitions-ensuring clean, bounce-free switching between modes. This capability is essential for SN74LVC16646ADGG applications requiring reliable arbitration between buffered and streaming data sources without introducing timing hazards.