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Texas Instruments SN74ALS641A-1DWR
- Part No.:
- SN74ALS641A-1DWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS641A-1DWR.pdf
- Description:
- IC TXRX INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,807
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Product details
Overview
SN74ALS641A-1DWR from Texas Instruments is a true-logic octal bidirectional bus transceiver in 20-pin SOIC (DW) package, designed for asynchronous two-way data transfer between A and B buses with direction control via DIR input and isolation via OE input. It supports 0°C to 70°C operation, delivers 48 mA low-level output current (IOL), and exhibits tPHL/tPLH propagation delays as low as 3 ns/5 ns under 50 pF load - used in legacy industrial backplane and memory expansion interfaces.
For engineers reviewing the SN74ALS641A-1DWR datasheet, SN74ALS641A-1DWR pinout, SN74ALS641A-1DWR application, or SN74ALS641A-1DWR equivalent, key selection considerations include its -1 version's enhanced 48 mA IOL rating, SOIC-20 thermal and layout compatibility, true-logic data path, and TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V).
Technical Context
This device implements dual 8-bit bidirectional data paths controlled by a single DIR signal: when DIR = L, data flows from B bus to A bus; when DIR = H, data flows from A bus to B bus. The OE input enables three-state output control, placing all A and B I/Os in high-impedance state when asserted high.
It operates strictly within TTL voltage domains (VCC = 4.5–5.5 V), features Schmitt-trigger inputs on control pins (DIR, OE), and maintains guaranteed VOL ≤ 0.5 V at IOL = 48 mA - a defining characteristic of the "-1" variant distinguishing it from standard SN74ALS641A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - compatible with standard 5-V TTL systems without regulation overhead |
| IOL (max) | 48 mA - enables direct drive of multiple TTL loads or moderate-current bus stubs |
| tPHL / tPLH | 3 ns / 5 ns - ensures sub-10 ns bidirectional latency critical for synchronous bus arbitration |
| VIH / VIL | 2.0 V / 0.8 V - matches standard TTL logic thresholds for seamless interface with 74LS/74ALS families |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade embedded control and instrumentation applications |
| VOL @ IOL=48mA | ≤ 0.5 V - guarantees noise margin > 0.4 V in worst-case 5-V TTL fanout scenarios |
| ICC (active) | 33–47 mA - reflects typical power draw during sustained bidirectional data transfer |
Pinout & Package
SN74ALS641A-1DWR uses a 20-pin SOIC (DW) package, 7.5 mm wide, 12.8 mm long, 2.65 mm max height, with 1.27 mm pitch and Pin 1 located in Quadrant Q1 per JEDEC MS-013.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction Control Input | Low = B→A data flow; High = A→B data flow; TTL-compatible threshold |
| 2 (A1) | Port A I/O | Bidirectional data line 1 for A bus; three-state when OE = H |
| 3–9 (A2–A8) | Port A I/Os | Remaining 7 bidirectional A-bus lines; identical electrical behavior to A1 |
| 10 (GND) | Ground Reference | Primary signal return for all I/O and internal logic; requires low-impedance PCB connection |
| 11–18 (B1–B8) | Port B I/Os | 8 bidirectional data lines for B bus; electrically symmetrical to A-port lines |
| 19 (VCC) | Power Supply | +5 V supply pin; requires local 0.1 µF ceramic decoupling adjacent to pin |
| 20 (OE) | Output Enable Input | High = all A/B I/Os in high-Z; Low = transceiver active; TTL-compatible |
Key Features
| Feature | Design Value |
|---|---|
| True-logic data path | Non-inverting A↔B transfer preserves signal polarity across both directions - essential for address/data bus integrity |
| -1 version IOL rating | 48 mA sink capability at VCC = 4.75–5.25 V enables driving heavier capacitive loads than standard ALS devices |
| Three-state bus isolation | Simultaneous high-impedance on all 16 I/Os when OE = H prevents bus contention in multi-master systems |
| TTL-compatible thresholds | VIH = 2.0 V and VIL = 0.8 V ensure interoperability with legacy 74LS, 74ALS, and microcontroller GPIOs |
| SOIC-20 footprint | Standard 1.27 mm pitch, 7.5 mm body width - supports automated assembly and fits dense PCB layouts |
Applications
| Industrial Backplane Interface | Legacy Memory Expansion |
|---|---|
Use Scenario: Bidirectional data routing between CPU module and peripheral cards in modular PLC chassis using shared parallel bus. IC Role / Device Role / Timing Role: Bus transceiver enabling A↔B communication under DIR-controlled direction and OE-gated isolation during card hot-swap. Use Value: 48 mA IOL drives long backplane traces with up to 8 TTL loads; sub-10 ns propagation ensures timing compliance with 20 MHz bus clocks. | Use Scenario: Extending 8-bit data/address bus between microcontroller and external SRAM or EPROM in retro-computing or test equipment. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled buffer between MCU data bus and memory device I/O pins. Use Value: True-logic path avoids inversion errors in address latching; VOL ≤ 0.5 V at 48 mA maintains TTL noise margin across full memory access cycle. |
| Microcontroller Peripheral Bridge | Test Equipment Signal Routing |
Use Scenario: Interfacing an 8-bit microcontroller port to external peripherals requiring independent read/write bus segments. IC Role / Device Role / Timing Role: Directional data conduit synchronized to MCU control signals (DIR = WR/RD#, OE = chip select). Use Value: tPHL/tPLH ≤ 5 ns allows integration into 12 MHz MCU bus cycles without wait states; SOIC-20 eases hand-soldering during lab prototyping. | Use Scenario: Reconfigurable signal path in automated test fixtures where DUT I/O must be routed to multiple instrument channels. IC Role / Device Role / Timing Role: Programmable bus switch controlled by test sequencer to isolate or connect DUT pins to stimulus/measurement resources. Use Value: Three-state isolation (OE) eliminates cross-talk during channel switching; 0°C–70°C rating supports benchtop thermal stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS641ADWR | Standard version with 24 mA IOL (not 48 mA); otherwise identical pinout, logic, and timing | Suitable only where bus loading is light (<4 TTL loads); cannot replace -1 version in high-drive designs | Select SN74ALS641ADWR only if verified IOL < 24 mA suffices; SN74ALS641A-1DWR required for full 48 mA drive. |
| SN74ALS642A-1DWR | Inverting logic path (A↔B data inverted); same -1 IOL rating, package, and timing specs | Used where system-level logic inversion is acceptable or compensated elsewhere (e.g., in firmware) | Choose SN74ALS642A-1DWR only if signal polarity inversion is architecturally tolerable; not functionally interchangeable. |
Compared with SN74ALS641ADWR, the SN74ALS641A-1DWR provides double the output drive strength for demanding bus loads, while SN74ALS642A-1DWR offers identical drive but inverted data - making the -1 variant essential for high-current true-logic bus bridging where neither reduced drive nor polarity flip is acceptable.
Availability
SN74ALS641A-1DWR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy memory expansion modules, and microcontroller peripheral bridges requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS641A-1DWR 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ALS641A-1DWR belongs to TI's legacy 74ALS logic family, engineered for robust 5-V TTL interoperability, high noise immunity, and reliable operation in commercial-temperature industrial control systems.
FAQ
What is the maximum output current rating for SN74ALS641A-1DWR?
The SN74ALS641A-1DWR is rated for a maximum low-level output current (IOL) of 48 mA when VCC is between 4.75 V and 5.25 V - a key differentiator from the standard SN74ALS641A (24 mA). This rating is validated per the SDAS300 datasheet Section "Recommended Operating Conditions" and applies to all 16 I/O pins simultaneously under specified thermal conditions. SN74ALS641A-1DWR maintains VOL ≤ 0.5 V at this drive level.
Is SN74ALS641A-1DWR pin-compatible with SN74ALS641ADWR?
Yes, SN74ALS641A-1DWR is fully pin-compatible with SN74ALS641ADWR: both use identical 20-pin SOIC (DW) packages, share the same pinout (DIR, A1–A8, GND, B1–B8, VCC, OE), and operate over the same 4.5–5.5 V VCC range. However, SN74ALS641A-1DWR delivers 48 mA IOL versus 24 mA for SN74ALS641ADWR - meaning mechanical replacement is possible, but functional equivalence requires verifying bus loading requirements.
Does SN74ALS641A-1DWR support hot-swap or live-insertion?
SN74ALS641A-1DWR is not explicitly rated for hot-swap operation. Its absolute maximum ratings specify VI ≤ 7 V on all I/Os, but no controlled slew-rate or bus-fault protection is integrated. For safe live insertion, external series resistors (e.g., 10–22 Ω) and current-limiting design practices are recommended. The device's three-state OE control enables software-coordinated isolation before physical insertion, but SN74ALS641A-1DWR itself lacks built-in hot-swap circuitry.
What is the operating temperature range for SN74ALS641A-1DWR?
SN74ALS641A-1DWR is characterized for operation from 0°C to 70°C, as confirmed in the "Recommended Operating Conditions" table of the SDAS300 datasheet. This commercial-grade temperature range aligns with standard industrial control and instrumentation environments but excludes extended temperature variants (e.g., −40°C to 85°C). Storage temperature is rated from −65°C to 150°C.
Can SN74ALS641A-1DWR interface directly with CMOS logic?
SN74ALS641A-1DWR can interface with 5-V CMOS (e.g., 74HC, CD4000) but requires careful design review: its VOH minimum is not specified beyond VCC – 0.5 V, and VIH = 2.0 V may fall below typical 5-V CMOS VIH (3.5 V). For reliable CMOS input recognition, pull-up resistors or level-shifting buffers are advised. SN74ALS641A-1DWR is optimized for TTL-family interoperability, not native CMOS voltage compatibility.
SN74ALS641A-1DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- Open Collector
- Current - Output High, Low:
- -, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74ALS641A-1DWR FAQ
1.How can I place an order for SN74ALS641A-1DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS641A-1DWR 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 SN74ALS641A-1DWR reliable?
The price and inventory of SN74ALS641A-1DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS641A-1DWR is usually 5 days.
3.What payment methods are accepted for SN74ALS641A-1DWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS641A-1DWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS641A-1DWR?
SN74ALS641A-1DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS641A-1DWR 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 SN74ALS641A-1DWR?
For technical support, including SN74ALS641A-1DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS641A-1DWR requirements.
6.How does Aetrix verify that SN74ALS641A-1DWR is sourced from the original manufacturer or authorized distributors?
All SN74ALS641A-1DWR 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 SN74ALS641A-1DWR meets industry standards.
7.What is the process for return or replacement of SN74ALS641A-1DWR?
All SN74ALS641A-1DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS641A-1DWR, 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 SN74ALS641A-1DWR part is unused and in its original packaging.
Return procedure for SN74ALS641A-1DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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