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Texas Instruments SN74ABT646ANT
- Part No.:
- SN74ABT646ANT
- Manufacturer:
- Texas Instruments
- Package:
- 24-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ABT646ANT.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,087
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Product details
Overview
SN74ABT646ANT from Texas Instruments is an octal bus transceiver with dual D-type registers, direction control, and output-enable logic for bidirectional data flow between A and B buses. It operates at 5 V, supports 125 MHz clock frequency, delivers ±32 mA/±64 mA drive strength, and features Ioff partial-power-down protection. It is used in high-speed backplane and motherboard bus interface applications requiring real-time or registered data transfer.
For engineers reviewing the SN74ABT646ANT datasheet, SN74ABT646ANT pinout, SN74ABT646ANT application, or SN74ABT646ANT equivalent, key selection criteria include its dual-clock (CLKAB/CLKBA) register control, SAB/SBA multiplexed output selection, DIR-driven direction arbitration, OE-gated tri-state operation, and compatibility with 5-V TTL-level systems requiring robust bus isolation and storage.
Technical Context
The SN74ABT646ANT integrates two independent 8-bit register banks synchronized to separate low-to-high clock edges-CLKAB latches A-bus data into B-register, CLKBA latches B-bus data into A-register. Its DIR input selects active bus direction during OE-enabled transceiver mode, while SAB and SBA enable real-time or stored data routing to outputs.
It implements true bidirectional bus management via four distinct functional modes: real-time A→B or B→A transfer, simultaneous A/B storage, and isolation with retained register contents. The Ioff circuitry ensures <±100 µA leakage when VCC = 0, enabling safe hot-insertion and partial power-down in mixed-supply systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply | 4.5 V to 5.5 V - compatible with standard 5-V TTL logic rails and noise margins |
| Max Clock Frequency | 125 MHz - enables high-throughput synchronous bus bridging in telecom and computing interfaces |
| Output Drive | −32 mA IOH / +64 mA IOL - drives heavy capacitive loads and long traces without external buffers |
| Ioff Leakage | ±100 µA at VCC = 0 - prevents backflow current during partial power-down, meeting JEDEC JESD-78 requirements |
| Propagation Delay | tPLH/tPHL ≤ 5.6 ns (CL = 50 pF) - supports sub-8 ns cycle timing for 125-MHz operation |
| ESD Rating | 2000-V HBM, 200-V MM - exceeds industrial-grade ESD immunity requirements per JESD22-A114/A115 |
| Operating Temp | −40°C to +85°C - qualified for commercial and extended-temperature embedded system deployment |
Pinout & Package
SN74ABT646ANT uses a 24-pin plastic dual-inline package (PDIP-NT) with 0.300-inch body width and through-hole mounting. Pin 1 is located at top-left corner with notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 inputs/outputs | 8-bit bidirectional data port A - connects to microprocessor or ASIC local bus |
| 9, 10, 11, 13, 14, 15, 16, 17 | B1–B8 inputs/outputs | 8-bit bidirectional data port B - interfaces to memory, peripheral, or backplane bus |
| 12 | GND | Ground reference for all logic and I/O circuits |
| 24 | VCC | 5-V supply rail - requires local 0.1 µF bypass capacitor |
| 18 | OE | Active-low output enable - places both A and B ports in high-impedance state when high |
| 19 | DIR | Direction control - determines destination bus (A or B) when OE is low |
| 20 | CLKAB | Low-to-high edge clock - loads A-bus data into B-register |
| 21 | CLKBA | Low-to-high edge clock - loads B-bus data into A-register |
| 22 | SAB | Select A-to-B - routes stored A-register or real-time A-bus data to B-port outputs |
| 23 | SBA | Select B-to-A - routes stored B-register or real-time B-bus data to A-port outputs |
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 output selection | SAB/SBA inputs select between transparent (real-time) or registered (latched) data on each output port |
| High-drive 5-V TTL outputs | −32 mA source / +64 mA sink capability eliminates need for external line drivers in dense PCB layouts |
| Ioff partial-power-down support | Prevents damaging current flow when VCC is off but A/B buses remain live - critical for hot-swap backplanes |
| Latch-up immunity >500 mA | Meets JEDEC JESD-17 - ensures robust operation under transient overvoltage or ESD stress conditions |
Applications
| Backplane Bus Interface | Memory Subsystem Bridge |
|---|---|
Use Scenario: Interfacing a CPU local bus to a multi-slot VME or CompactPCI backplane with isolated timing domains. IC Role / Device Role / Timing Role: Bidirectional bus transceiver with register staging to absorb clock domain skew and reduce metastability risk. Use Value: Enables deterministic 125-MHz data handoff between asynchronous clock zones while maintaining signal integrity across 15+ inch traces. | Use Scenario: Connecting a 32-bit RISC processor to dual-channel SDRAM or SRAM modules with independent address/data multiplexing. IC Role / Device Role / Timing Role: Direction-controlled data path with CLKBA-synchronized write capture and CLKAB-synchronized read forwarding. Use Value: Eliminates external latch logic and reduces PCB layer count by integrating dual-edge register functionality in one 24-pin IC. |
| Hot-Swappable Module Controller | Industrial PLC I/O Expansion |
Use Scenario: Managing data exchange between a main controller and field-replaceable I/O modules in modular automation racks. IC Role / Device Role / Timing Role: Isolation-mode register hold during module insertion/removal; Ioff prevents backfeeding into powered-down slots. Use Value: Guarantees zero-current injection during hot-swap events, satisfying IEC 61000-4-2 Level 4 ESD and UL 61000-1-2 safety requirements. | Use Scenario: Extending digital I/O capacity of a programmable logic controller via daisy-chained expansion cards with shared data bus. IC Role / Device Role / Timing Role: DIR- and OE-governed bus arbitration; SAB/SBA-selectable register bypass for deterministic scan-cycle latency. Use Value: Reduces worst-case I/O update latency by 3.5 ns versus discrete latch + transceiver solutions, improving PLC scan time consistency. |
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 |
|---|---|---|---|
| SN74ABT245DW | No internal registers; single-direction control (DIR only); no CLKAB/CLKBA or SAB/SBA logic | Suitable for simple level-shifting or unidirectional buffering, not for registered bus arbitration | Choose when only basic 8-bit bidirectional buffering is needed without clocked storage or multiplexed output selection |
| SN74LVTH16646DL | Lower voltage (3.3 V), LVTH logic family; 16-bit (dual-octal); different pinout and control signal mapping | Designed for 3.3-V systems with higher density; incompatible with 5-V SN74ABT646ANT PCB layout | Choose for new 3.3-V designs requiring higher channel count and lower power, not for drop-in replacement |
Compared with SN74ABT245DW and SN74LVTH16646DL, the SN74ABT646ANT uniquely provides dual-clock register staging, SAB/SBA multiplexing, and 5-V TTL drive in a 24-pin PDIP - making it irreplaceable in legacy 5-V backplane and industrial control systems requiring precise timing control and hot-swap safety.
Availability
SN74ABT646ANT is available at Aetrix Electronics and suitable for backplane interface, memory subsystem bridge, hot-swappable module controller, and industrial PLC I/O expansion applications requiring stable component supply across extended product lifecycles.
Supply support for SN74ABT646ANT 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 for industrial, automotive, and communications markets.
The SN74ABT646ANT belongs to TI's ABT logic family, engineered for high-speed 5-V TTL-compatible bus management in mission-critical infrastructure where reliability, drive strength, and partial-power-down safety are mandatory.
FAQ
What is the function of the SAB and SBA pins on the SN74ABT646ANT?
The SAB (Select A-to-B) and SBA (Select B-to-A) pins on the SN74ABT646ANT determine whether the A-port or B-port outputs deliver real-time bus data or stored register data. When SAB is low, real-time A-bus data appears on B outputs; when high, stored A-register data is routed instead. SBA operates symmetrically for B-to-A transfer. This multiplexing enables flexible data routing without external logic, directly supporting four bus-management modes defined in the datasheet.
Does the SN74ABT646ANT support hot-swap operation?
Yes, the SN74ABT646ANT supports hot-swap operation via its Ioff circuitry, which disables outputs and limits leakage current to ±100 µA when VCC = 0 V. This prevents damaging current backflow from live A/B buses into a powered-down device - a requirement for compliant hot-plug systems. TI specifies this behavior per JEDEC JESD-78, and the SN74ABT646ANT has been validated in backplane applications where modules are inserted or removed under power.
What is the maximum clock frequency supported by the SN74ABT646ANT?
The SN74ABT646ANT supports a maximum clock frequency of 125 MHz under recommended operating conditions (VCC = 5 V, TA = 25°C). This is confirmed by timing parameter fmax in the switching characteristics table. At this rate, setup time (tsu) is 3 ns and hold time (th) is 0 ns for data relative to CLKAB↑ or CLKBA↑, enabling tight-tolerance synchronous bus interfacing in high-performance computing and telecom equipment.
Can the SN74ABT646ANT operate at 3.3 V?
No, the SN74ABT646ANT is specified only for 4.5 V to 5.5 V supply operation and is not rated for reliable 3.3-V use. Its input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output drive characteristics are optimized for 5-V TTL logic families. Attempting 3.3-V operation risks marginal noise margins, reduced drive strength, and potential functional failure. For 3.3-V systems, TI recommends the SN74LVTH16646 or similar LVTH-family devices.
How does the DIR pin control data flow in the SN74ABT646ANT?
The DIR (direction-control) pin on the SN74ABT646ANT determines the destination bus during transceiver mode (when OE is low). When DIR = low, data flows from B-bus to A-bus; when DIR = high, data flows from A-bus to B-bus. DIR has no effect in isolation mode (OE = high), where both ports remain high-impedance and internal registers retain their stored values. This pin enables software-configurable bidirectional data routing without changing clock or select signals.
SN74ABT646ANT 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
SN74ABT646ANT FAQ
1.How can I place an order for SN74ABT646ANT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT646ANT 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 SN74ABT646ANT reliable?
The price and inventory of SN74ABT646ANT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT646ANT is usually 5 days.
3.What payment methods are accepted for SN74ABT646ANT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ABT646ANT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ABT646ANT?
SN74ABT646ANT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ABT646ANT 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 SN74ABT646ANT?
For technical support, including SN74ABT646ANT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT646ANT requirements.
6.How does Aetrix verify that SN74ABT646ANT is sourced from the original manufacturer or authorized distributors?
All SN74ABT646ANT 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 SN74ABT646ANT meets industry standards.
7.What is the process for return or replacement of SN74ABT646ANT?
All SN74ABT646ANT units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT646ANT, 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 SN74ABT646ANT part is unused and in its original packaging.
Return procedure for SN74ABT646ANT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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