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Texas Instruments SN74ABT646DGVR
- Part No.:
- SN74ABT646DGVR
- Manufacturer:
- Texas Instruments
- Package:
- 24-TFSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74ABT646DGVR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24TVSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,957
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Product details
Overview
SN74ABT646 from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, designed for bidirectional data flow control between two 8-bit buses (A and B). It integrates D-type flip-flops, clocked storage (CLKAB/CLKBA), direction control (DIR), output enable (OE), and select logic (SAB/SBA), supporting real-time or registered transfer at up to 125 MHz. It operates from 4.5 V to 5.5 V and is rated for –40°C to 85°C, commonly used in backplane interface, memory expansion, and system-level bus isolation.
For engineers reviewing the SN74ABT646 datasheet, SN74ABT646 pinout, SN74ABT646 application, or SN74ABT646 equivalent, this page delivers verified functional architecture, DB-package–specific pin mapping, timing-critical parameters (tPLH/tPHL < 8 ns), high-drive capability (–32 mA IOH / 64 mA IOL), and validated alternatives for industrial bus management designs.
Technical Context
The SN74ABT646 implements dual-clock synchronous storage: CLKAB latches A-bus data into internal registers, while CLKBA latches B-bus data - both on low-to-high transitions. DIR selects bus direction during active transfer, and OE enables/disables 3-state outputs independently of input functionality.
Its EPIC-IIB BiCMOS process enables high-speed operation (125 MHz max clock) with low ground bounce (<1 V VOLP) and robust latch-up immunity (>500 mA per JESD-17). Real-time and registered modes are selected via SAB/SBA, allowing simultaneous storage and transparent transfer without bus contention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5-V TTL and CMOS systems |
| Max Clock Frequency | 125 MHz - supports high-throughput data routing in fast parallel interfaces |
| Output Drive | –32 mA IOH / 64 mA IOL - drives heavy capacitive loads and multiple TTL inputs without external buffers |
| Propagation Delay | tPLH/tPHL ≤ 7.8 ns (A↔B) - enables sub-8-ns bus turnaround critical for cycle-accurate timing |
| Operating Temperature | –40°C to 85°C - qualified for industrial-grade embedded and computing applications |
| Input Clamp Current | –18 mA - protects against transient overvoltage on control pins per MIL-STD-883C |
| ESD Rating | >2000 V HBM - meets stringent electrostatic discharge requirements for board-level handling |
Pinout & Package
SN74ABT646DGVR uses a 24-pin Shrink Small-Outline Package (SSOP, DB), measuring 7.9 mm × 4.5 mm × 1.2 mm (max height), with 0.65 mm lead pitch and Q1 pin-1 orientation. The package is RoHS-compliant, moisture-sensitivity Level-1, and optimized for high-density PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | CLKAB | Clock input controlling latching of A-bus data into internal register |
| 2 | SAB | Select input enabling real-time or stored A→B transfer when DIR = H |
| 3 | DIR | Direction control: H = A→B, L = B→A (active when OE = L) |
| 4–11 | A1–A8 | 8-bit bidirectional data port A - functions as input or 3-state output |
| 12 | GND | Power ground reference for all internal circuitry and I/O |
| 13–20 | B1–B8 | 8-bit bidirectional data port B - functions as input or 3-state output |
| 21 | OE | Active-low output enable - forces A/B ports into high-impedance state when high |
| 22 | SBA | Select input enabling real-time or stored B→A transfer when DIR = L |
| 23 | CLKBA | Clock input controlling latching of B-bus data into internal register |
| 24 | VCC | Positive supply rail (4.5–5.5 V) powering BiCMOS core and I/O drivers |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent clock domains | CLKAB and CLKBA allow asynchronous registration of A- and B-bus data without cross-domain timing constraints |
| Multiplexed transfer modes | SAB/SBA enable runtime selection between real-time (transparent) and registered (latched) data paths |
| High-drive 3-state outputs | –32 mA IOH / 64 mA IOL supports fan-out to ≥10 standard TTL loads with minimal signal degradation |
| Input-enabled during output disable | When OE = H, A/B ports remain active inputs - enabling continuous data capture while outputs are isolated |
| Low ground bounce | VOLP < 1 V at VCC = 5 V ensures signal integrity in noise-sensitive mixed-signal environments |
Applications
| Backplane Data Routing | Memory Expansion Interface |
|---|---|
Use Scenario: Isolating and synchronizing data between CPU and peripheral modules across a shared 8-bit backplane. IC Role / Device Role / Timing Role: SN74ABT646 acts as a registered bus transceiver, buffering and clocking data between address/data lanes while preventing bus contention. Use Value: Enables deterministic 125-MHz bus arbitration with sub-8-ns propagation delay and simultaneous A/B storage for pipelined transfers. | Use Scenario: Extending 8-bit microcontroller address/data bus to external SRAM or Flash memory arrays. IC Role / Device Role / Timing Role: SN74ABT646 serves as a direction-controlled bidirectional buffer with clocked register hold, aligning memory access timing to controller cycles. Use Value: Provides high-drive outputs (64 mA IOL) to drive long traces and multiple memory devices, while OE/DIR sequencing prevents data corruption during read/write transitions. |
| Industrial PLC I/O Module | Digital Signal Processor (DSP) Co-Processor Link |
Use Scenario: Interfacing field I/O cards with a central controller using isolated, noise-immune parallel communication. IC Role / Device Role / Timing Role: SN74ABT646 functions as a fault-tolerant bus isolator, storing sensor/actuator data on CLKAB/CLKBA edges and transferring only upon valid DIR/OE assertion. Use Value: ESD protection (>2000 V HBM) and latch-up immunity (>500 mA) ensure reliability in electrically harsh factory environments. | Use Scenario: Connecting a DSP's external memory interface to a co-processor or FPGA-based accelerator over a shared 8-bit data path. IC Role / Device Role / Timing Role: SN74ABT646 operates as a synchronized data multiplexer, selecting between real-time DSP output and pre-stored configuration data via SAB/SBA. Use Value: Dual-clock architecture allows concurrent data preparation and transfer, reducing inter-processor latency by eliminating software handshake overhead. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver and register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ABT245DW | No internal registers; lacks CLKAB/CLKBA, SAB/SBA - only real-time transceiver mode | Cannot store or pipeline data; suitable only for simple level-shifting or bus extension without timing control | Choose when clocked storage is unnecessary and cost or footprint is prioritized over functionality |
| SN74LVTH16245ADGGR | 16-bit, dual-supply (3.3 V core / 5 V I/O), no clock inputs - register-free, lower drive (–24 mA / 24 mA) | Designed for 3.3 V–5 V translation in modern low-voltage systems; not drop-in compatible due to pin count and feature set | Choose for newer 3.3 V architectures requiring voltage translation, not for legacy 5 V registered bus designs |
Compared with SN74ABT245DW and SN74LVTH16245ADGGR, the SN74ABT646 uniquely combines octal bidirectional 3-state I/O with dual-edge-triggered registers and multiplexed transfer control - making it irreplaceable where deterministic, clock-aligned bus arbitration and data staging are required.
Availability
SN74ABT646DGVR is available at Aetrix Electronics and suitable for industrial backplane routing, memory expansion interfaces, PLC I/O modules, and DSP co-processor links requiring stable component supply across extended product lifecycles.
Supply support for SN74ABT646DGVR 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 heritage in high-reliability interface ICs.
The SN74ABT646 belongs to TI's ABT logic family, engineered for high-speed, low-noise 5-V bus management in industrial and computing systems where timing precision and drive strength are critical.
FAQ
What is the function of the SAB and SBA pins on the SN74ABT646?
The SAB (Select A→B) and SBA (Select B→A) pins determine whether real-time (transparent) or registered (latched) data is transferred across the bus. When SAB = L and DIR = H, real-time A-bus data flows to B; when SAB = H, stored A-data is output. Similarly, SBA controls B→A transfer mode. This multiplexing is essential for flexible data staging in the SN74ABT646.
Can the SN74ABT646 operate with a 3.3-V supply?
No - the SN74ABT646 is specified only for 4.5 V to 5.5 V operation. Its EPIC-IIB BiCMOS process and input thresholds (VIH = 2 V min, VIL = 0.8 V max) are optimized for 5-V TTL compatibility. Using 3.3 V violates recommended operating conditions and risks unreliable logic levels or failure to meet timing specs.
How does the SN74ABT646 handle power-up sequencing to avoid bus contention?
To ensure high-impedance outputs at power-up, OE must be tied to VCC through a pull-up resistor. TI specifies the minimum resistance based on driver sink capability; typical values range from 4.7 kΩ to 10 kΩ. This guarantees that OE remains high until system firmware asserts control, preventing unintended bus driving by the SN74ABT646 during startup.
What is the maximum capacitive load the SN74ABT646 can drive while maintaining timing specifications?
The SN74ABT646 switching characteristics (e.g., tPLH/tPHL) are characterized with CL = 50 pF. While higher capacitance may be driven due to its 64-mA IOL, propagation delays increase linearly beyond this point. For designs exceeding 50 pF, timing margins must be re-verified using the device's output impedance model and board trace parameters - the SN74ABT646 itself does not guarantee spec compliance above CL = 50 pF.
Is the SN74ABT646 pin-compatible with the SN74ABT640 or SN74ABT642?
No - the SN74ABT646 has a unique 24-pin DB/DW/PW pinout with dedicated CLKAB, CLKBA, SAB, and SBA signals. The SN74ABT640 (24-pin) lacks clocks and select logic; the SN74ABT642 (20-pin) is a non-registering transceiver with different pin count and assignment. None share pin-for-pin compatibility with the SN74ABT646.
SN74ABT646DGVR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ABT
- Package/Case:
- 24-TFSOP (0.173", 4.40mm 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-TVSOP
SN74ABT646DGVR FAQ
1.How can I place an order for SN74ABT646DGVR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT646DGVR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
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The price and inventory of SN74ABT646DGVR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT646DGVR is usually 5 days.
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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 SN74ABT646DGVR?
For technical support, including SN74ABT646DGVR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT646DGVR requirements.
6.How does Aetrix verify that SN74ABT646DGVR is sourced from the original manufacturer or authorized distributors?
All SN74ABT646DGVR 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 SN74ABT646DGVR meets industry standards.
7.What is the process for return or replacement of SN74ABT646DGVR?
All SN74ABT646DGVR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT646DGVR, 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 SN74ABT646DGVR part is unused and in its original packaging.
Return procedure for SN74ABT646DGVR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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