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Texas Instruments SN74LVC646ADW
- Part No.:
- SN74LVC646ADW
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74LVC646ADW.pdf
- Description:
- IC TXRX NON-INVERT 3.6V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:500
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Product details
Overview
SN74LVC646ADW from Texas Instruments is an octal bus transceiver and register with 3-state outputs, designed for bidirectional data flow between two 8-bit buses (A and B) under clocked register control. It operates from 1.65 V to 3.6 V, supports mixed-mode 5-V/3.3-V I/O, and features Ioff partial-power-down protection. Used in system-level bus isolation, data buffering, and synchronous bus arbitration in industrial controllers and FPGA interconnects.
For engineers reviewing the SN74LVC646ADW datasheet, SN74LVC646ADW pinout, SN74LVC646ADW application, or SN74LVC646ADW equivalent, key selection criteria include its dual-clock (CLKAB/CLKBA) register staging, DIR/OE/SAB/SBA control flexibility, 7.4 ns max tpd at 3.3 V, 24-pin SOIC (DW) package, and guaranteed 150 MHz clock frequency support.
Technical Context
The SN74LVC646ADW integrates eight D-type flip-flops per bus, enabling independent latching of A- or B-bus data on low-to-high transitions of CLKAB or CLKBA. Its control logic allows four distinct bus-management modes: real-time transfer, stored-data transfer, isolated storage, and transparent pass-through - all selectable via OE, DIR, SAB, and SBA inputs.
It implements true 3-state output drivers with Ioff circuitry that disables outputs during power-down, preventing backflow current. Inputs tolerate up to 5.5 V regardless of VCC, enabling safe interfacing between 3.3-V logic domains and legacy 5-V systems without level shifters.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 1.65 V to 3.6 V - Enables operation across low-voltage microcontrollers and mixed-supply systems. |
| Max Clock Frequency | 150 MHz - Supports high-speed synchronous bus handshaking in real-time control applications. |
| Propagation Delay (tpd) | 7.4 ns at 3.3 V - Ensures timing-critical data paths meet setup/hold requirements in fast digital systems. |
| Ioff Support | Yes - Prevents damaging current flow when VCC = 0 V, critical for hot-swap and partial-power-down designs. |
| Input Voltage Tolerance | Up to 5.5 V - Allows direct connection to 5-V peripherals without external level translation. |
| Output Drive Strength | ±24 mA at 3.0 V - Sufficient to drive multiple LVC loads or moderate PCB trace capacitance. |
| Operating Temperature | –40°C to +85°C - Qualified for industrial-grade embedded systems and automation equipment. |
Pinout & Package
SN74LVC646ADW uses a 24-pin SOIC (DW) package with 0.65 mm lead pitch and 7.5 mm × 15.4 mm body dimensions. Pin 1 is located at the top-left corner adjacent to the index notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | CLKAB | Clock input controlling latching of A-bus data into internal register A. |
| 2 | SAB | Select input enabling real-time or stored A-bus data routing to B-bus output. |
| 3 | DIR | Direction control: Low = A←B transfer; High = A→B transfer (when OE low). |
| 4–11 | A1–A8 | 8-bit bidirectional data port A - connects to master or local bus segment. |
| 12 | GND | Ground reference for all internal logic and I/O circuits. |
| 13 | VCC | Primary supply voltage (1.65–3.6 V) powering core logic and output drivers. |
| 14 | CLKBA | Clock input controlling latching of B-bus data into internal register B. |
| 15 | SBA | Select input enabling real-time or stored B-bus data routing to A-bus output. |
| 16 | OE | Output enable: High = all outputs in high-impedance state; Low = outputs active per DIR/SAB/SBA. |
| 17–24 | B1–B8 | 8-bit bidirectional data port B - connects to peripheral or secondary bus segment. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent clock domains | Separate CLKAB and CLKBA inputs allow asynchronous registration of A- and B-bus data without cross-domain timing constraints. |
| Mixed-voltage I/O compatibility | 5.5-V-tolerant inputs enable seamless integration between 3.3-V logic and 5-V legacy peripherals in heterogeneous systems. |
| Configurable bus management | Four operational modes (real-time transfer, stored-data transfer, isolation, hold) are selected via OE, DIR, SAB, and SBA - no external logic required. |
| Partial-power-down protection | Ioff circuitry ensures outputs remain high-impedance and non-conductive when VCC = 0 V, eliminating backfeed risk in modular power architectures. |
| Low propagation delay | 7.4 ns max tpd at 3.3 V enables use in high-frequency data pipelines where cycle time budgets are tight. |
Applications
| Industrial PLC Backplane Interface | FPGA-to-Microcontroller Bridge |
|---|---|
Use Scenario: Isolating and synchronizing data between a 5-V I/O module and a 3.3-V FPGA-based controller in a programmable logic controller rack. IC Role / Device Role / Timing Role: Bidirectional bus transceiver with register staging; provides clock-aligned data capture and controlled output enable for deterministic bus arbitration. Use Value: Eliminates need for discrete level shifters and external latches while supporting 150 MHz clock rates for real-time I/O scanning. |
Use Scenario: Interfacing a 3.3-V ARM Cortex-M7 microcontroller with an FPGA configured as a high-speed peripheral accelerator. IC Role / Device Role / Timing Role: Octal registered transceiver managing synchronous command/response traffic over parallel address/data bus. Use Value: Enables glitch-free handshaking using DIR and OE to decouple read/write phases, with SAB/SBA selecting between buffered and live data paths. |
| Automotive Body Control Module | Test Equipment Data Acquisition Bus |
Use Scenario: Buffering sensor data from multiple 5-V analog front-ends to a 3.3-V MCU in a vehicle body control unit with strict power sequencing. IC Role / Device Role / Timing Role: Registered bus interface with Ioff support - maintains isolation during MCU power-up/down sequences. Use Value: Prevents back-current injection into unpowered MCU pins during cold-start or sleep/wake transitions, meeting ISO 16750-2 requirements. |
Use Scenario: Multiplexing high-speed digitizer outputs onto a shared test-system backplane operating at variable voltage levels (1.8 V, 2.5 V, 3.3 V). IC Role / Device Role / Timing Role: Programmable bus register enabling synchronized sampling and burst-mode data forwarding to host processor. Use Value: Reduces FPGA resource usage by offloading register staging and bus direction control, improving test throughput and reducing firmware complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC646APW | TSSOP-24 package (4.4 mm × 5.0 mm), 0.65 mm pitch; same electrical specs and pinout as SN74LVC646ADW. | Better suited for space-constrained PCB layouts requiring smaller footprint and improved thermal dissipation. | Select SN74LVC646APW when board area is limited and reflow-compatible assembly is available. |
| SN74LVC646ADBR | SSOP-24 package (5.3 mm × 7.2 mm), 0.635 mm pitch; identical functional behavior and timing performance. | Offers higher pin-to-pin creepage/clearance for enhanced noise immunity in industrial environments. | Choose SN74LVC646ADBR for applications demanding robust ESD margin and mechanical stability in vibration-prone enclosures. |
Compared with SN74LVC646APW and SN74LVC646ADBR, the SN74LVC646ADW provides the largest pad pitch (1.27 mm) and highest solder joint reliability in manual or wave-soldered assemblies, making it preferred for prototyping, repair, and high-reliability industrial manufacturing.
Availability
SN74LVC646ADW is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA-to-MCU bridges, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74LVC646ADW 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 decades of experience in industrial, automotive, and communications markets.
The SN74LVC646ADW belongs to TI's LVC logic family, engineered for low-voltage, high-speed, mixed-signal interoperability in systems requiring robust bus management, voltage translation, and power-aware design.
FAQ
What is the maximum clock frequency supported by the SN74LVC646ADW?
The SN74LVC646ADW supports a maximum clock frequency of 150 MHz across its full operating voltage range (1.65 V to 3.6 V). This specification is validated per TI's switching characteristics table and applies to both CLKAB and CLKBA inputs under recommended operating conditions, ensuring reliable register staging in high-speed synchronous bus applications.
Does the SN74LVC646ADW support 5-V input signals while powered at 3.3 V?
Yes, the SN74LVC646ADW accepts input voltages up to 5.5 V regardless of VCC level - including when VCC = 3.3 V. This feature is explicitly documented in the Recommended Operating Conditions table and enables direct interfacing with 5-V peripherals without external level-shifting circuitry, simplifying mixed-voltage system design.
How does the Ioff feature function in the SN74LVC646ADW?
The Ioff circuitry in the SN74LVC646ADW disables all outputs when VCC = 0 V, preventing current backflow from live buses into the unpowered device. This behavior is verified in the Electrical Characteristics table (Ioff ≤ ±10 µA at VI/VO = 5.5 V) and is essential for safe partial-power-down operation in modular or hot-swap-capable systems.
What are the key differences between SN74LVC646ADW and SN74LVC646APW?
The SN74LVC646ADW (SOIC-24) and SN74LVC646APW (TSSOP-24) share identical logic functionality, timing, and electrical specifications. The primary difference is package: DW offers 1.27 mm lead pitch and 7.5 mm × 15.4 mm body size, while PW uses 0.65 mm pitch and 4.4 mm × 5.0 mm footprint - making PW more compact but requiring finer-pitch assembly capability.
Can the SN74LVC646ADW operate reliably at 1.65 V supply voltage?
Yes, the SN74LVC646ADW is fully specified down to 1.65 V, with guaranteed parameters including VIH/VIL thresholds, output drive strength (±4 mA at 1.65 V), and 150 MHz clock operation. This low-voltage capability is confirmed in the Recommended Operating Conditions table and supports energy-efficient designs in battery-powered or ultra-low-power embedded systems.
SN74LVC646ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LVC
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 24mA, 24mA
- Voltage - Supply:
- 1.65V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74LVC646ADW FAQ
1.How can I place an order for SN74LVC646ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LVC646ADW on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN74LVC646ADW reliable?
The price and inventory of SN74LVC646ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LVC646ADW is usually 5 days.
3.What payment methods are accepted for SN74LVC646ADW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LVC646ADW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LVC646ADW?
SN74LVC646ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LVC646ADW order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN74LVC646ADW?
For technical support, including SN74LVC646ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LVC646ADW requirements.
6.How does Aetrix verify that SN74LVC646ADW is sourced from the original manufacturer or authorized distributors?
All SN74LVC646ADW products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74LVC646ADW meets industry standards.
7.What is the process for return or replacement of SN74LVC646ADW?
All SN74LVC646ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74LVC646ADW, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN74LVC646ADW part is unused and in its original packaging.
Return procedure for SN74LVC646ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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