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Texas Instruments SN74LVC646APW
- Part No.:
- SN74LVC646APW
- Manufacturer:
- Texas Instruments
- Package:
- 24-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74LVC646APW.pdf
- Description:
- IC TXRX NON-INVERT 3.6V 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,774
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Product details
Overview
SN74LVC646APW 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. It is used in system-level bus isolation, data buffering, and synchronous bus arbitration in industrial controllers and FPGA interconnects.
For engineers reviewing the SN74LVC646APW datasheet, SN74LVC646APW pinout, SN74LVC646APW application, or SN74LVC646APW equivalent, key selection considerations include its dual-clock register architecture (CLKAB/CLKBA), direction-controlled 3-state output enable (DIR/OE), select-multiplexed real-time vs. stored data routing (SAB/SBA), and TSSOP-24 package compatibility with high-density PCB layouts.
Technical Context
The SN74LVC646APW integrates eight independent bidirectional channels, each with D-type flip-flops clocked on the low-to-high transition of CLKAB (A→B) or CLKBA (B→A). Its control logic enables four distinct bus-management modes: real-time transfer, stored-data transfer, storage-only, and isolation - all governed by OE, DIR, SAB, and SBA inputs.
It implements Ioff circuitry to disable outputs during power-down, preventing backflow current when VCC = 0 V, and accepts input voltages up to 5.5 V regardless of VCC level - enabling direct interfacing between 3.3-V logic and legacy 5-V systems without external level shifters.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 1.65 V to 3.6 V - supports single-supply operation across low-voltage embedded and mixed-voltage system rails. |
| Max Clock Frequency | 150 MHz at VCC = 3.3 V - enables high-speed synchronous bus handshaking in real-time control interfaces. |
| tpd (Propagation Delay) | 7.4 ns at VCC = 3.3 V - ensures tight timing margins for 100+ MHz data paths in FPGA-to-ASIC bridging. |
| Ioff Current | ±10 µA at VI/VO = 5.5 V - guarantees safe partial-power-down behavior in hot-swap and power-gated subsystems. |
| Input Voltage Tolerance | 0 V to 5.5 V - allows direct connection to 5-V TTL outputs without level-shifting components. |
| Output Drive Strength | ±24 mA at VCC = 3.0 V - drives standard 50-Ω transmission lines or multiple CMOS loads in backplane applications. |
| Package | TSSOP-24 (PW) - 0.65-mm pitch, 7.9 mm × 4.5 mm footprint optimized for automated assembly and thermal relief. |
Pinout & Package
TSSOP-24 (PW) package: 7.9 mm × 4.5 mm body, 0.65 mm lead pitch, 1.2 mm max height, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4–10, 15–22 | A1–A8, B1–B8 | 8-bit bidirectional data terminals for Bus A and Bus B; support 5-V-tolerant inputs and 3.3-V 3-state outputs. |
| 3, 23 | DIR, OE | Direction control (DIR) selects data flow direction; Output Enable (OE) globally disables all outputs to high-impedance state. |
| 11, 12, 24 | GND, VCC, CLKAB | Ground reference, 1.65–3.6 V supply, and clock input for latching data from Bus A into internal registers. |
| 13, 14, 21 | CLKBA, SAB, SBA | CLKBA clocks data from Bus B; SAB/SBA select real-time or stored data routing for A→B and B→A transfers respectively. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent clock domains | Separate CLKAB and CLKBA inputs allow asynchronous registration of data from either bus, enabling flexible pipeline staging. |
| Mixed-voltage I/O compatibility | 5.5-V-tolerant inputs operate reliably with 5-V drivers while powered from 1.65–3.6 V, eliminating external translators. |
| Four-mode bus management | Real-time transfer, stored-data transfer, isolation, and storage modes are selected via OE/DIR/SAB/SBA - simplifying complex bus arbitration logic. |
| Ioff partial-power-down protection | Outputs automatically enter high-Z when VCC = 0 V, preventing current backflow in multi-rail systems during power sequencing. |
| Low ground bounce (VOLP) | Typical VOLP < 0.8 V at VCC = 3.3 V - reduces noise coupling in high-speed digital systems with shared ground planes. |
Applications
| Industrial PLC Backplane Interface | FPGA-to-Microcontroller Data Bridge |
|---|---|
Use Scenario: Bidirectional data exchange between a 3.3-V FPGA and legacy 5-V I/O modules in programmable logic controller racks. IC Role / Device Role / Timing Role: SN74LVC646APW acts as a registered transceiver, synchronizing data transfers using CLKAB/CLKBA and isolating voltage domains. Use Value: Enables deterministic timing alignment and eliminates level-shifter components, reducing BOM count and board area. | Use Scenario: High-speed command/status handshaking between a Xilinx Artix-7 FPGA and an ARM Cortex-M7 microcontroller operating at different supply voltages. IC Role / Device Role / Timing Role: SN74LVC646APW serves as a clocked bus register, decoupling FPGA and MCU clock domains while maintaining data integrity. Use Value: Provides setup/hold time margin (tsu = 1.6 ns, th = 1.7 ns at 3.3 V) and 7.4-ns propagation delay for sub-100-ns cycle times. |
| Automotive Body Control Module | Test Equipment Digital Pattern Generator |
Use Scenario: Isolating and buffering sensor data streams between 3.3-V ADCs and 5-V CAN transceivers in automotive body electronics. IC Role / Device Role / Timing Role: SN74LVC646APW functions as a voltage-translating bus register, storing sensor samples on CLKBA and forwarding them on demand via DIR/OE control. Use Value: Ioff protection prevents latch-up during battery disconnect events; 5.5-V input tolerance accommodates noisy 5-V CAN bus signaling. | Use Scenario: Generating synchronized 8-bit stimulus patterns for IC functional testing, where precise edge-aligned data must be driven onto DUT pins. IC Role / Device Role / Timing Role: SN74LVC646APW operates as a pattern register, loading test vectors on CLKAB and driving them onto Bus B under DIR/OE control. Use Value: 150-MHz max clock frequency and 7.4-ns tpd ensure accurate pattern delivery at >100 Mbps test speeds. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC646ADBR | SSOP-24 package (7.0 mm × 5.3 mm), higher θJA (65°C/W), same electrical specs and pinout. | Preferred for through-hole prototyping or legacy SSOP-compatible footprints; less suitable for ultra-dense layouts. | Select SN74LVC646ADBR if board space permits larger package or reflow profile requires slower thermal ramp rates. |
| SN74LVC646APWR | Identical TSSOP-24 package and specs; supplied in 2000-piece tape-and-reel vs. 60-piece tube (SN74LVC646APW). | Optimized for high-volume automated assembly; identical performance and layout compatibility. | Choose SN74LVC646APWR for production runs requiring reel-fed pick-and-place; SN74LVC646APW suits low-volume evaluation or repair. |
Compared with SN74LVC646ADBR and SN74LVC646APWR, the SN74LVC646APW offers identical core functionality and timing in a compact TSSOP-24 tube format - making it ideal for design validation, small-batch builds, and field replacement where reel logistics are impractical.
Availability
SN74LVC646APW is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA-to-MCU bridges, and automotive body control modules requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for SN74LVC646APW 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, precision, and energy efficiency.
The SN74LVC646A product line targets high-speed, low-voltage bus interface applications in industrial automation, communications infrastructure, and automotive electronics - prioritizing mixed-voltage interoperability and robust power sequencing behavior.
FAQ
What is the maximum clock frequency supported by the SN74LVC646APW?
The SN74LVC646APW supports a maximum clock frequency of 150 MHz when operated at VCC = 3.3 V, as specified in the timing characteristics table. At lower supply voltages (e.g., 1.8 V), this value is not published in the datasheet, and actual usable frequency depends on process variation and board-level signal integrity. For reliable operation across temperature and voltage ranges, TI recommends derating to ≤125 MHz in production designs using SN74LVC646APW.
Does the SN74LVC646APW support 5-V input signals while powered from 3.3 V?
Yes, the SN74LVC646APW supports input voltages up to 5.5 V regardless of VCC level - including when VCC = 3.3 V. This 5-V-tolerant input capability is explicitly guaranteed in the Recommended Operating Conditions table and enables direct interfacing with legacy 5-V logic families without external level shifters. The SN74LVC646APW maintains full functionality and timing compliance under this mixed-voltage condition.
How does the Ioff feature function in the SN74LVC646APW during power-down?
The Ioff feature in the SN74LVC646APW disables all output buffers when VCC = 0 V, limiting leakage current to ±10 µA even if input or output pins are driven to 5.5 V. This prevents damaging backflow current through the device during partial power-down sequences - a critical requirement in multi-rail systems like industrial controllers. The SN74LVC646APW remains electrically isolated without requiring external pull-up/down resistors on I/O lines.
What are the key differences between SN74LVC646APW and SN74LVC646APWR?
The SN74LVC646APW and SN74LVC646APWR share identical electrical specifications, pinout, package dimensions, and thermal characteristics - differing only in packaging format: SN74LVC646APW is supplied in a 60-piece tube, while SN74LVC646APWR uses a 2000-piece tape-and-reel. Both are TSSOP-24 (PW) devices with NIPDAU lead finish and MSL Level-1 rating. The SN74LVC646APW is intended for prototyping and low-volume use; SN74LVC646APWR suits high-throughput SMT assembly.
Can the SN74LVC646APW operate reliably at 1.65 V supply voltage?
Yes, the SN74LVC646APW is fully specified to operate down to VCC = 1.65 V, as confirmed in the Recommended Operating Conditions table. At this minimum voltage, DC parameters such as VOH (≥1.2 V at IOH = –100 µA) and VOL (≤0.45 V at IOL = 100 µA) remain valid, and AC timing parameters are defined for VCC ≥ 1.65 V. However, maximum clock frequency and propagation delay degrade at lower VCC; for 1.65 V operation, consult TI's characterization data or perform board-level validation with SN74LVC646APW.
SN74LVC646APW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LVC
- Package/Case:
- 24-TSSOP (0.173", 4.40mm 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-TSSOP
SN74LVC646APW FAQ
1.How can I place an order for SN74LVC646APW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LVC646APW 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 SN74LVC646APW reliable?
The price and inventory of SN74LVC646APW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LVC646APW is usually 5 days.
3.What payment methods are accepted for SN74LVC646APW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LVC646APW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LVC646APW?
SN74LVC646APW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LVC646APW 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 SN74LVC646APW?
For technical support, including SN74LVC646APW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LVC646APW requirements.
6.How does Aetrix verify that SN74LVC646APW is sourced from the original manufacturer or authorized distributors?
All SN74LVC646APW 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 SN74LVC646APW meets industry standards.
7.What is the process for return or replacement of SN74LVC646APW?
All SN74LVC646APW units undergo pre-shipment inspection (PSI). If there is an issue with SN74LVC646APW, 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 SN74LVC646APW part is unused and in its original packaging.
Return procedure for SN74LVC646APW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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