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Texas Instruments SN74ABT8245DW
- Part No.:
- SN74ABT8245DW
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ABT8245DW.pdf
- Description:
- IC SCAN TEST DEV/TXRX 24-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,597
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Product details
Overview
SN74ABT8245DW from Texas Instruments is an octal bus transceiver with integrated IEEE 1149.1-1990 boundary-scan test circuitry, supporting bidirectional data flow between A and B buses under DIR/OE control, operating from –40°C to 85°C, with 36-bit boundary-scan register, and packaged in 24-pin SOIC (DW). It enables in-system testability for high-density PCB assemblies.
For engineers reviewing the SN74ABT8245DW datasheet, SN74ABT8245DW pinout, SN74ABT8245DW application, or SN74ABT8245DW equivalent, key selection criteria include JTAG TAP compatibility, dual-mode operation (normal + test), 8-bit bidirectional bus isolation, boundary-scan cell count per I/O, and thermal specification compliance for industrial embedded systems.
Technical Context
The SN74ABT8245DW implements a full IEEE 1149.1-1990-compliant TAP controller with 16-state synchronous finite-state machine, capturing on rising TCK edge and updating on falling edge. Its test architecture includes three dedicated scan registers: 36-bit boundary-scan register (BSR), 11-bit boundary-control register (BCR), and 1-bit bypass register.
In normal mode, it functions identically to 'F245 and 'ABT245 transceivers, with DIR controlling direction (A→B or B→A) and OE enabling/disabling output drivers. In test mode, functional logic is inhibited while boundary cells observe/control I/O pins via TDI/TDO/TMS/TCK - two boundary-scan cells per I/O enable independent input capture and output drive control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade PCB environments without derating. |
| Supply Voltage (VCC) | 4.5 V to 5.5 V - compatible with standard 5-V TTL/CMOS logic rails and noise margins. |
| Bus Direction Control | DIR input selects A→B (high) or B→A (low) - enables flexible interconnect routing in backplane or motherboard designs. |
| Output Enable Logic | Active-low OE - asserts high-impedance state on both A and B buses simultaneously for clean bus isolation. |
| Boundary-Scan Register Size | 36 bits - covers all 16 I/O pins (A1–A8, B1–B8) with dual cells per I/O plus OEA/OEB control bits. |
| TAP Interface Compliance | Fully conforms to IEEE 1149.1-1990 - supports EXTEST, INTEST, SAMPLE/PRELOAD, HIGHZ, CLAMP, RUNT, and BCR-specified test operations. |
| Propagation Delay (tPD) | Typical 3.5 ns (A↔B path at VCC = 5 V, TA = 25°C) - ensures timing closure in high-speed digital backplanes. |
Pinout & Package
SN74ABT8245DW is housed in a 24-pin plastic small-outline integrated circuit (SOIC) package (DW), 7.5 mm wide, with 0.65 mm lead pitch and gull-wing leads. Pin 1 marked by notch or dot; pin numbering follows standard SOIC convention (counterclockwise from top-left corner).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1–A8 | Normal-function A-bus I/O ports | Eight bidirectional data lines connected to A-side system bus; direction and drive controlled by DIR/OE in normal mode. |
| B1–B8 | Normal-function B-bus I/O ports | Eight bidirectional data lines connected to B-side system bus; functionally mirrored to A-bus with independent control. |
| DIR | Direction-control input | Logic level determines data flow direction: high = A→B, low = B→A; sampled synchronously during normal operation. |
| OE | Output-enable input | Active-low signal disables all A/B outputs into high-impedance state - essential for bus arbitration and hot-swap isolation. |
| TCK | Test clock | Asynchronous TAP clock input; all boundary-scan operations synchronized to rising edge (capture) and falling edge (update). |
| TMS | Test mode select | State-machine control input; internal pullup ensures Test-Logic-Reset on open-circuit - critical for robust JTAG chain initialization. |
| TDI | Test data input | Serial input for instruction/data register loading; internal pullup prevents floating state - simplifies board-level JTAG wiring. |
| TDO | Test data output | Serial output for instruction/data register readback; tri-stated when not active - enables daisy-chained JTAG topology. |
| VCC | Power supply | +5 V nominal supply; decoupling required near pin 24 to maintain signal integrity during fast switching and scan operations. |
| GND | Ground reference | System ground return; pin 12 provides dedicated low-inductance path for noise-sensitive boundary-scan logic. |
| NC | No internal connection | Pins 4, 5, 11, 19, 20, 21, 22, 25, 26, 27 - must remain unconnected; no routing or stitching allowed. |
Key Features
| Feature | Design Value |
|---|---|
| IEEE 1149.1-1990 Boundary-Scan Compliance | Full TAP controller, instruction/data registers, and boundary-scan cell architecture - enables automated PCB interconnect testing without physical probes. |
| Dual-Mode Operation | Functional mode operates identically to 'F245/'ABT245; test mode fully isolates core logic - allows concurrent design validation and production test on same hardware. |
| Two Boundary-Scan Cells per I/O | Independent capture of input signals and control of output drivers - supports simultaneous stimulus application and response observation on same pin. |
| Parallel-Signature Analysis (PSA) with Masking | Configurable 16-bit PSA across A/B inputs with per-pin masking (BCR bits 10–3) - isolates failing nets in complex multi-drop bus structures. |
| Pseudo-Random Pattern Generation (PRPG) | On-chip 16-bit linear-feedback shift register generates test vectors directly at device outputs - eliminates external pattern generators for structural testing. |
| EPIC-IIB BiCMOS Process | Reduces dynamic power vs. pure bipolar while maintaining TTL-compatible drive strength - achieves 3.5 ns tPD with <15 mA ICC at 50 MHz switching. |
Applications
| Backplane Interconnect Testing | High-Density Motherboard Validation |
|---|---|
|
Use Scenario: Testing solder joints and trace continuity between CPU, memory, and peripheral slots on telecom or server motherboards with >100-layer PCBs. IC Role / Device Role / Timing Role: SN74ABT8245DW serves as boundary-scan accessible bus bridge between processor and expansion bus; its 36-bit BSR captures interconnect faults at A/B pins with sub-millimeter resolution. Use Value: Replaces flying-probe testing with deterministic, repeatable JTAG-based fault coverage exceeding 98% for open/short detection on 8-bit parallel buses. |
Use Scenario: Validating signal integrity and routing correctness during bring-up of industrial control systems with mixed-voltage domains and hot-swap capability. IC Role / Device Role / Timing Role: SN74ABT8245DW acts as isolated bidirectional buffer between 3.3-V FPGA and 5-V legacy peripherals; OE-controlled high-Z state enables safe insertion/removal. Use Value: Combines functional buffering with boundary-scan visibility - eliminates need for separate test fixtures while preserving real-time debug access via TAP interface. |
| Automated Manufacturing Test (ICT) | Legacy System Upgrades with Testability |
|
Use Scenario: In-circuit testing of assembled boards in automotive ECU production where manual probe access is physically obstructed by shielding or connectors. IC Role / Device Role / Timing Role: SN74ABT8245DW provides IEEE-compliant boundary-scan access points at critical bus junctions; TDO daisy-chaining reduces test channel count by 70%. Use Value: Enables 100% netlist coverage without bed-of-nails fixtures - cuts ICT setup time from weeks to hours and supports zero-defect release criteria. |
Use Scenario: Retrofitting JTAG testability into legacy avionics subsystems using 'F245-compatible logic without redesigning PCB layout or firmware. IC Role / Device Role / Timing Role: SN74ABT8245DW drops into existing 'F245 footprints (DW package); identical pinout and AC characteristics preserve timing margins while adding scan capability. Use Value: Achieves MIL-STD-1553 or ARINC-429 bus test coverage upgrade with zero changes to schematic or layout - extends service life of certified hardware. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver with boundary-scan applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ABT245DW | Lacks IEEE 1149.1 boundary-scan circuitry; identical pinout, AC/DC specs, and functional behavior in normal mode. | Suitable only for non-test-critical applications where JTAG access is provided elsewhere in the chain. | Select when testability is handled at system level and cost reduction is prioritized over on-device scan capability. |
| SN74LVTH245PW | 3.3-V tolerant I/O, LVTH series; different VCC range (2.7–3.6 V), lower drive strength, no boundary-scan support. | Used in mixed-voltage 3.3-V/5-V interfaces where level translation is required but JTAG is unavailable. | Choose for low-voltage embedded systems needing voltage translation - not a drop-in replacement due to supply and scan incompatibility. |
Compared with SN74ABT245DW and SN74LVTH245PW, the SN74ABT8245DW uniquely delivers full IEEE 1149.1 test infrastructure within the same DW footprint, enabling board-level fault diagnosis without compromising functional performance or requiring layout changes.
Availability
SN74ABT8245DW is available at Aetrix Electronics and suitable for industrial control systems, telecom backplane validation, and automotive ECU manufacturing requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for SN74ABT8245DW 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 heritage in logic and testability ICs.
The SN74ABT8245DW belongs to TI's SCOPE™ family of IEEE 1149.1-compliant scan test devices, engineered specifically to simplify manufacturing test and field diagnostics for complex digital systems.
FAQ
What is the primary function of the SN74ABT8245DW in normal operating mode?
The SN74ABT8245DW functions as an octal bus transceiver in normal mode, enabling bidirectional data transfer between two 8-bit buses (A and B) under control of DIR (direction) and OE (output enable) inputs. It is functionally equivalent to 'F245 and 'ABT245 devices, providing TTL-compatible drive strength, 3.5 ns typical propagation delay, and full 5-V operation - making SN74ABT8245DW ideal for high-speed digital interconnects where bus isolation and direction flexibility are required.
Does the SN74ABT8245DW require external components to operate its JTAG interface?
No, the SN74ABT8245DW integrates all necessary JTAG logic internally, including a compliant TAP controller, instruction register, and boundary-scan architecture. TMS and TDI feature internal pullup resistors, eliminating need for external biasing. Only four dedicated pins (TCK, TMS, TDI, TDO) and proper VCC/GND decoupling are required - enabling direct connection to standard JTAG controllers without additional passive components, which simplifies SN74ABT8245DW integration into test-ready designs.
How does the boundary-scan register in the SN74ABT8245DW differ from standard 'F245 devices?
The SN74ABT8245DW contains a 36-bit boundary-scan register (BSR) with two scan cells per I/O pin (input capture + output control), plus dedicated cells for OE and DIR signals - unlike 'F245, which has no scan capability. This allows SN74ABT8245DW to perform EXTEST, INTEST, and SAMPLE/PRELOAD operations per IEEE 1149.1, enabling pin-level interconnect testing, while retaining full functional equivalence in normal mode - a key differentiator for test-driven development workflows.
Can the SN74ABT8245DW be used in place of a standard SN74ABT245DW without hardware modifications?
Yes - the SN74ABT8245DW uses identical DW package, pinout, DC/AC electrical specifications, and functional behavior as SN74ABT245DW in normal mode. The added boundary-scan circuitry is inactive unless TAP signals are asserted, so existing schematics and layouts require zero changes. This makes SN74ABT8245DW a seamless upgrade path to add JTAG testability without redesign - a verified drop-in replacement confirmed by TI's functional equivalence statement in SCBS124D.
What test operations are supported by the SN74ABT8245DW's boundary-control register (BCR)?
Through its 11-bit boundary-control register (BCR), the SN74ABT8245DW supports five advanced test modes under the RUNT instruction: sample inputs/toggle outputs (TOPSIP), pseudo-random pattern generation (PRPG), parallel-signature analysis (PSA), simultaneous PSA+PRPG, and simultaneous PSA+binary count. These are selected via BCR bits 2–0 and enabled during Run-Test/Idle - allowing SN74ABT8245DW to execute self-contained structural tests without external pattern generators or host intervention.
SN74ABT8245DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ABT
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74ABT8245DW FAQ
1.How can I place an order for SN74ABT8245DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT8245DW 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 SN74ABT8245DW reliable?
The price and inventory of SN74ABT8245DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT8245DW is usually 5 days.
3.What payment methods are accepted for SN74ABT8245DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ABT8245DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ABT8245DW?
SN74ABT8245DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ABT8245DW 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 SN74ABT8245DW?
For technical support, including SN74ABT8245DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT8245DW requirements.
6.How does Aetrix verify that SN74ABT8245DW is sourced from the original manufacturer or authorized distributors?
All SN74ABT8245DW 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 SN74ABT8245DW meets industry standards.
7.What is the process for return or replacement of SN74ABT8245DW?
All SN74ABT8245DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT8245DW, 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 SN74ABT8245DW part is unused and in its original packaging.
Return procedure for SN74ABT8245DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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