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Texas Instruments SN74LVTH646DWR
- Part No.:
- SN74LVTH646DWR
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74LVTH646DWR.pdf
- Description:
- IC TXRX NON-INVERT 3.6V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,870
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Product details
Overview
SN74LVTH646DWR from Texas Instruments is a 3.3-V octal bus transceiver with registers, supporting mixed-mode 5-V/3.3-V interfacing, hot insertion via Ioff and power-up 3-state, and bus-hold on all data inputs. It features dual-clock (CLKAB/CLKBA), direction control (DIR), output enable (OE), and select controls (SAB/SBA) for multiplexed A↔B data routing in industrial backplanes and legacy system upgrades.
For engineers reviewing the SN74LVTH646DWR datasheet, SN74LVTH646DWR pinout, SN74LVTH646DWR application, or SN74LVTH646DWR equivalent, key selection criteria include 3.3-V VCC operation with 5-V tolerant I/O, 150-MHz clock frequency support, bus-hold elimination of external resistors, and SOIC-24 package compatibility with legacy PCB layouts.
Technical Context
The SN74LVTH646DWR integrates eight bidirectional data channels, each with D-type flip-flop registers clocked on low-to-high transitions of CLKAB or CLKBA. Its dual-register architecture enables independent storage of A-bus and B-bus data, allowing real-time or registered transfer based on DIR, OE, SAB, and SBA logic states.
It implements active bus-hold circuitry on all A1–A8 and B1–B8 inputs (±75 µA hold current at VCC = 3 V), supports unregulated battery operation down to 2.7 V, and meets JESD 17 latch-up (>500 mA) and JESD 22 ESD standards (2000-V HBM, 200-V MM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply Range | 2.7 V to 3.6 V - Enables direct connection to 3.3-V rails and tolerance for brownout conditions in portable or battery-backed systems. |
| Input Voltage Tolerance | Up to 5.5 V - Allows safe interfacing with 5-V TTL logic without level shifters in mixed-voltage backplane designs. |
| Max Clock Frequency | 150 MHz - Supports high-speed synchronous bus transfers in data acquisition and communications subsystems. |
| Output Drive Strength | IOL = 64 mA / IOH = −32 mA at VCC = 3 V - Drives standard TTL loads and multiple CMOS inputs without buffering. |
| Bus-Hold Current | ±75 µA at VCC = 3 V - Maintains valid logic levels on floating data lines, eliminating need for external pullup/pulldown resistors. |
| Propagation Delay | tPLH/tPHL ≤ 5.6 ns (A↔B), ≤ 6.7 ns (OE/DIR control) - Ensures timing closure in sub-7-ns critical paths for register-to-bus transfers. |
| Hot-Insertion Support | Ioff ≤ ±100 µA at VCC = 0 V - Prevents backflow current during live board insertion, protecting upstream drivers and power supplies. |
Pinout & Package
SN74LVTH646DWR is housed in a 24-pin SOIC (DW) package, 7.5 mm × 4.4 mm body, 1.27 mm pitch, with gull-wing leads and RoHS-compliant NiPdAu finish (MSL Level-1, 260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4–10, 13–20 | A1–A8, B1–B8 Data I/O | Bidirectional data terminals with bus-hold; A-side connects to local processor bus, B-side to peripheral or legacy interface. |
| 3 | DIR | Direction control: Low = B→A transfer, High = A→B transfer; determines data flow path when OE is active. |
| 11 | OE | Output enable: Low = transceiver active, High = high-impedance isolation; tied to VCC via pullup for safe power-up state. |
| 12, 23 | CLKAB, CLKBA | Register clocks: CLKAB latches A-bus data into A-register; CLKBA latches B-bus data into B-register. |
| 2, 22 | SAB, SBA | Select controls: SAB = 0 enables real-time B→A transfer; SBA = 0 enables real-time A→B transfer. |
| 21, 24 | GND, VCC | Power terminals: Single 3.3-V supply rail; decoupling capacitor required within 1 cm of VCC/GND pins. |
| 14, 15, 16, 21 | NC | No internal connection - must remain unconnected; no routing or thermal relief required. |
Key Features
| Feature | Design Value |
|---|---|
| Mixed-mode 5-V/3.3-V I/O | 5-V-tolerant inputs and outputs operate safely with 3.3-V VCC, enabling seamless integration between legacy 5-V peripherals and modern 3.3-V controllers. |
| Integrated bus-hold | Eliminates external pullup/pulldown resistors on all 16 data lines, reducing BOM count, PCB area, and signal integrity risk from stubs or mismatched terminations. |
| Hot-insertion support | Ioff and power-up 3-state prevent current backflow and bus contention during live insertion, meeting requirements for modular telecom and industrial rack systems. |
| Dual-register multiplexing | Independent A-register and B-register allow simultaneous storage of data from both buses, enabling time-multiplexed access or glitch-free handshaking protocols. |
| TTL-compatible thresholds | VIH = 2.0 V, VIL = 0.8 V at VCC = 3.3 V - Ensures reliable recognition of standard TTL logic levels without additional voltage translation. |
Applications
| Industrial Backplane Interface | Legacy System Upgrade Bridge |
|---|---|
|
Use Scenario: Connecting a modern 3.3-V FPGA-based controller to an existing 5-V ISA or VME bus in factory automation equipment. IC Role / Device Role / Timing Role: Bidirectional level-translating transceiver with registered data capture, synchronizing asynchronous bus cycles using CLKAB/CLKBA edges. Use Value: Eliminates discrete level shifters and glue logic while preserving timing margins via 5.6-ns A↔B propagation delay and 150-MHz clock support. |
Use Scenario: Upgrading a 5-V microcontroller-based medical instrument with a new 3.3-V ADC/DAC module without redesigning the main PCB. IC Role / Device Role / Timing Role: Bus-isolation and data-multiplexing hub that stores legacy sensor data in A-register and forwards processed results from B-register. Use Value: Bus-hold prevents floating inputs during firmware transition phases; OE/DIR control allows runtime reconfiguration of data flow direction. |
| Modular Telecom Shelf | Test Equipment Signal Routing |
|
Use Scenario: Hot-pluggable line card in a carrier-grade switch where control plane (3.3-V) must communicate with legacy 5-V PHY modules. IC Role / Device Role / Timing Role: Hot-insertion–qualified bus transceiver managing command/response traffic between management CPU and service modules. Use Value: Ioff ≤ ±100 µA ensures zero backfeed current during insertion; power-up 3-state avoids bus conflicts before firmware initialization. |
Use Scenario: Automated test system requiring programmable routing of stimulus signals between multiple DUT interfaces operating at different voltage domains. IC Role / Device Role / Timing Role: Configurable register-based multiplexer controlled by FPGA GPIOs (DIR, OE, SAB, SBA) to route calibrated analog/digital signals. Use Value: Real-time and stored transfer modes enable deterministic signal switching with sub-7-ns latency; NC pins simplify layout for multi-channel boards. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus transceiver with register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC646APW | 3.3-V only I/O (no 5-V tolerance); lower drive (IOL = 24 mA); no bus-hold; TSSOP-24 package. | Requires external level shifters for 5-V systems; suitable only for pure 3.3-V environments with light loading. | Choose SN74LVC646APW only if cost and board space are prioritized over mixed-voltage flexibility and bus-hold convenience. |
| SN74LVCH16646DL | 16-bit (dual-octal), 3.3-V VCC, 5-V tolerant, bus-hold, but 56-pin SSOP package; higher pin count and larger footprint. | Designed for wider data buses (e.g., 16-bit memory expansion); not drop-in compatible due to pinout and package mismatch. | Choose SN74LVCH16646DL only when scaling to 16-bit parallel interfaces is required; not a replacement for SN74LVTH646DWR's 24-pin SOIC footprint. |
Compared with SN74LVC646APW, SN74LVTH646DWR provides essential 5-V I/O tolerance and bus-hold for legacy integration, while SN74LVCH16646DL offers double width at the cost of PCB area and pin compatibility-neither serves as a pin-for-pin substitute, making SN74LVTH646DWR uniquely suited for compact 8-bit mixed-voltage bridging.
Availability
SN74LVTH646DWR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system upgrade bridges, and modular telecom shelf designs requiring stable component supply across extended product lifecycles.
Supply support for SN74LVTH646DWR 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 IC design.
The SN74LVTH646DWR belongs to TI's LVTH logic family, engineered for robust mixed-signal interfacing in harsh environments-designed specifically to bridge voltage domains while maintaining signal integrity, timing precision, and system reliability.
FAQ
What is the maximum clock frequency supported by the SN74LVTH646DWR?
The SN74LVTH646DWR supports a maximum clock frequency of 150 MHz under recommended operating conditions (VCC = 3.3 V ± 0.3 V). This specification applies to both CLKAB and CLKBA inputs and is validated across the full industrial temperature range (−40°C to 85°C), ensuring reliable register capture in high-speed data acquisition and communication subsystems.
Does the SN74LVTH646DWR require external pullup resistors on its data inputs?
No, the SN74LVTH646DWR does not require external pullup or pulldown resistors on A1–A8 or B1–B8 inputs because it integrates active bus-hold circuitry. This feature maintains valid logic levels on unused or floating inputs with ±75 µA hold current at VCC = 3 V, simplifying design and improving noise immunity in unterminated bus segments.
Can the SN74LVTH646DWR be used in hot-swap applications?
Yes, the SN74LVTH646DWR is explicitly designed for hot-insertion applications. Its Ioff circuitry limits current to ±100 µA when VCC = 0 V, preventing damaging backflow, and its power-up 3-state functionality places outputs in high-impedance during power ramp-up-both features verified per TI's SCBS705H datasheet and JESD standards.
What package type is used for the SN74LVTH646DWR?
The SN74LVTH646DWR uses a 24-pin SOIC (DW) package: 7.5 mm × 4.4 mm body, 1.27 mm lead pitch, gull-wing leads, RoHS-compliant NiPdAu surface finish, and MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH). This package matches legacy footprints and supports automated assembly with standard reflow profiles.
How does the SN74LVTH646DWR handle 5-V input signals while operating at 3.3-V VCC?
The SN74LVTH646DWR accepts input voltages up to 5.5 V regardless of VCC setting (2.7–3.6 V), thanks to its 5-V-tolerant input structure. Internal clamping and protection circuitry ensure safe operation without external components-enabling direct connection to 5-V TTL outputs while maintaining 3.3-V logic thresholds (VIH = 2.0 V, VIL = 0.8 V) for clean signal interpretation.
SN74LVTH646DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LVTH
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- 32mA, 64mA
- Voltage - Supply:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74LVTH646DWR FAQ
1.How can I place an order for SN74LVTH646DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LVTH646DWR 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 SN74LVTH646DWR reliable?
The price and inventory of SN74LVTH646DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LVTH646DWR is usually 5 days.
3.What payment methods are accepted for SN74LVTH646DWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LVTH646DWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LVTH646DWR?
SN74LVTH646DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LVTH646DWR 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 SN74LVTH646DWR?
For technical support, including SN74LVTH646DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LVTH646DWR requirements.
6.How does Aetrix verify that SN74LVTH646DWR is sourced from the original manufacturer or authorized distributors?
All SN74LVTH646DWR 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 SN74LVTH646DWR meets industry standards.
7.What is the process for return or replacement of SN74LVTH646DWR?
All SN74LVTH646DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LVTH646DWR, 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 SN74LVTH646DWR part is unused and in its original packaging.
Return procedure for SN74LVTH646DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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