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Texas Instruments SN74ABT646NT
- Part No.:
- SN74ABT646NT
- Manufacturer:
- Texas Instruments
- Package:
- 24-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ABT646NT.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,905
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Product details
Overview
SN74ABT646NT from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, designed for bidirectional data flow control between A and B buses in high-speed digital systems. It features dual clock inputs (CLKAB/CLKBA), direction control (DIR), output enable (OE), and select controls (SAB/SBA), supporting real-time or registered data transfer at up to 125 MHz with ±32-mA high-drive outputs.
For engineers reviewing the SN74ABT646NT datasheet, SN74ABT646NT pinout, SN74ABT646NT application, or SN74ABT646NT equivalent, key selection considerations include its 24-pin plastic DIP (NT) package, -40°C to 85°C industrial temperature range, BiCMOS EPIC-IIB process enabling low power dissipation, and support for bus isolation, storage, and multiplexed transfer modes.
Technical Context
This device integrates eight independent bidirectional channels, each combining a D-type flip-flop register and a 3-state transceiver. Data is latched on the low-to-high transition of CLKAB (A→B) or CLKBA (B→A), while DIR selects bus direction and OE enables/disables output drivers.
The SAB and SBA inputs determine whether real-time or stored data appears on the output bus; when OE is high, both A and B buses enter high-impedance isolation while internal registers retain stored values. The NT package variant uses through-hole mounting and supports 5-V operation only.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with standard 5-V TTL/CMOS logic systems without level-shifting. |
| Max Clock Frequency | 125 MHz - Enables high-throughput data transfer in fast synchronous bus architectures. |
| Output Drive | -32 mA IOH / +64 mA IOL - Provides robust noise immunity and fan-out capability for driving multiple loads. |
| Propagation Delay | 1.5 ns to 8.4 ns - Guarantees tight timing margins in critical control-path applications. |
| Operating Temperature | -40°C to +85°C - Qualified for industrial environments including factory automation and instrumentation. |
| Input Clamp Current | -18 mA - Protects against transient overvoltage events per MIL-STD-883C Method 3015. |
| Power Dissipation (NT) | 1.3 W at TA = 55°C - Defines thermal design requirements for PCB layout and heatsinking. |
Pinout & Package
The SN74ABT646NT is housed in a 24-pin plastic dual in-line package (PDIP), designated NT, with 0.6-inch body width and through-hole mounting. Pin 1 is located at the top-left corner with notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | CLKAB | Clock input for latching data from A bus into B-side register on rising edge. |
| 2 | SAB | Select input controlling whether real-time or stored A-bus data drives B bus. |
| 3 | DIR | Direction control: low = B→A, high = A→B during transceiver mode (OE low). |
| 4–11 | A1–A8 | 8-bit A-side bidirectional data bus interface with internal register and 3-state driver. |
| 12 | GND | Ground reference for all internal circuitry and I/O signaling. |
| 13–20 | B1–B8 | 8-bit B-side bidirectional data bus interface with internal register and 3-state driver. |
| 21 | OE | Active-low output enable: high = isolation mode (all outputs high-Z), low = transceiver active. |
| 22 | SBA | Select input controlling whether real-time or stored B-bus data drives A bus. |
| 23 | CLKBA | Clock input for latching data from B bus into A-side register on rising edge. |
| 24 | VCC | Positive supply rail (4.5–5.5 V) powering internal BiCMOS logic and output drivers. |
Key Features
| Feature | Design Value |
|---|---|
| EPIC-IIB BiCMOS Process | Reduces static and dynamic power consumption versus standard bipolar TTL while maintaining speed. |
| High-Drive Outputs | Delivers -32 mA source / +64 mA sink current to drive heavy capacitive loads and long traces reliably. |
| Four Bus Management Modes | Supports real-time transfer, storage, isolation, and stored-data transfer via combinational control inputs. |
| Output Ground Bounce (VOLP) | Typically <1 V at VCC = 5 V - Minimizes signal integrity degradation during simultaneous switching. |
| ESD Protection | Exceeds 2000 V HBM and 200 V machine model - Enhances handling robustness in manufacturing and field service. |
Applications
| Industrial PLC Backplane Interface | Legacy ISA Bus Extension |
|---|---|
Use Scenario: Interfacing microcontroller-based I/O modules to a centralized backplane in programmable logic controllers. IC Role / Device Role / Timing Role: SN74ABT646NT acts as a registered bus transceiver, buffering and synchronizing data between local module registers and shared backplane address/data lines. Use Value: Enables deterministic timing via clocked register staging, preventing metastability during hot-swap or asynchronous bus arbitration. | Use Scenario: Extending legacy ISA bus signals to additional peripheral cards in retro-computing or test equipment platforms. IC Role / Device Role / Timing Role: SN74ABT646NT serves as a bidirectional bus repeater with direction control, allowing expansion slots to share main system address and data paths. Use Value: Maintains signal integrity across extended trace lengths using high-drive outputs and low ground bounce characteristics. |
| Test Equipment Signal Routing | Automated Test Fixture Control |
Use Scenario: Dynamic reconfiguration of signal paths between DUT ports and measurement instruments in ATE systems. IC Role / Device Role / Timing Role: SN74ABT646NT functions as a programmable bus switch with storage, allowing preloaded test patterns to be routed on demand. Use Value: Eliminates need for external latch logic by integrating register + transceiver in one package, reducing component count and board area. | Use Scenario: Controlling parallel I/O lines between controller and fixture actuators/sensors in production line test fixtures. IC Role / Device Role / Timing Role: SN74ABT646NT operates in isolation mode to hold fixture state during controller reset, then resumes synchronized communication. Use Value: Prevents spurious actuator activation during power-up/down sequences via OE-controlled high-Z default state. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ABT245N | Lacks internal registers; only provides transparent transceiver function without clocked storage. | Suitable for simple level translation or bus extension where timing registration is unnecessary. | Choose SN74ABT245N when real-time pass-through suffices and register functionality adds cost/complexity. |
| SN74LVT646PW | Uses LVT BiCMOS process; operates at 3.3 V only; lower drive (-24/+24 mA); different pinout (TSSOP-24). | Targeted for mixed-voltage 3.3-V systems interfacing to 5-V peripherals via level shifters. | Choose SN74LVT646PW only if migrating to 3.3-V core logic and accepting reduced drive strength and non-pin-compatible packaging. |
Compared with SN74ABT245N and SN74LVT646PW, the SN74ABT646NT uniquely combines 5-V operation, high-drive capability, integrated clocked registers, and through-hole NT packaging-making it irreplaceable in legacy industrial designs requiring deterministic bus staging and mechanical reliability.
Availability
SN74ABT646NT is available at Aetrix Electronics and suitable for industrial control backplanes, legacy computer bus extensions, automated test fixture interfaces, and embedded instrumentation requiring stable component supply across long product lifecycles.
Supply support for SN74ABT646NT 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 for industrial, automotive, and communications markets.
The SN74ABT646NT belongs to TI's ABT advanced BiCMOS logic family, engineered for high-speed, low-power registered bus interface applications in demanding industrial environments.
FAQ
What is the maximum clock frequency supported by the SN74ABT646NT?
The SN74ABT646NT supports a maximum clock frequency of 125 MHz under recommended operating conditions (VCC = 5 V, TA = 25°C). This rating applies to both CLKAB and CLKBA inputs and ensures reliable setup/hold timing for data latching into internal registers. At temperature extremes or reduced supply voltage, the usable frequency may decrease due to increased propagation delay.
Does the SN74ABT646NT require external pull-up resistors on control pins?
Yes - to ensure high-impedance state during power-up or power-down, OE must be tied to VCC through a pull-up resistor. The minimum resistance value depends on the current-sinking capability of the driving source but typically ranges from 4.7 kΩ to 10 kΩ. Unused SAB, SBA, DIR, CLKAB, and CLKBA inputs should also be held high or low to prevent floating states that increase power consumption or cause erratic behavior.
Can the SN74ABT646NT operate at 3.3 V?
No - the SN74ABT646NT is specified only for 4.5 V to 5.5 V operation. Its BiCMOS EPIC-IIB process and input thresholds are optimized for 5-V TTL compatibility. Attempting to operate below 4.5 V risks violating VIH/VIL specifications, leading to unreliable logic levels and potential functional failure. For 3.3-V systems, consider TI's LVT or ALVC families instead.
How does the SN74ABT646NT handle simultaneous access to both A and B buses?
The SN74ABT646NT enforces strict bus arbitration: only one of the two buses (A or B) may be actively driven at any time. When OE is low and DIR is set, data flows unidirectionally; when OE is high, both buses enter high-impedance isolation regardless of DIR state. Internal registers retain stored values independently, but output drivers never assert conflicting signals on A and B simultaneously.
Is the SN74ABT646NT RoHS compliant?
Yes - the SN74ABT646NT meets RoHS Directive 2011/65/EU requirements. It contains no lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), or polybrominated diphenyl ethers (PBDE). The NT package uses lead-free finish on leads and complies with TI's standard environmental specifications for industrial-grade components.
SN74ABT646NT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ABT
- Package/Case:
- 24-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- Through Hole
- Supplier Device Package:
- 24-PDIP
SN74ABT646NT FAQ
1.How can I place an order for SN74ABT646NT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT646NT 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 SN74ABT646NT reliable?
The price and inventory of SN74ABT646NT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT646NT is usually 5 days.
3.What payment methods are accepted for SN74ABT646NT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ABT646NT transactions.
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4.How is shipping managed for SN74ABT646NT?
SN74ABT646NT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ABT646NT 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 SN74ABT646NT?
For technical support, including SN74ABT646NT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT646NT requirements.
6.How does Aetrix verify that SN74ABT646NT is sourced from the original manufacturer or authorized distributors?
All SN74ABT646NT 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 SN74ABT646NT meets industry standards.
7.What is the process for return or replacement of SN74ABT646NT?
All SN74ABT646NT units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT646NT, 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 SN74ABT646NT part is unused and in its original packaging.
Return procedure for SN74ABT646NT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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