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Texas Instruments SN74ALS641ADWR
- Part No.:
- SN74ALS641ADWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS641ADWR.pdf
- Description:
- IC TXRX INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,044
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Product details
Overview
SN74ALS641ADWR from Texas Instruments is an octal bidirectional bus transceiver in a 20-pin SOIC (DW) package, implementing true logic with direction-control (DIR) and output-enable (OE) inputs. It supports asynchronous two-way data transfer between A and B buses at up to 48 mA low-level output current, with propagation delays as low as 3 ns (tPHL), and operates across 0°C to 70°C for industrial bus interface applications.
For engineers reviewing the SN74ALS641ADWR datasheet, SN74ALS641ADWR pinout, SN74ALS641ADWR application, or SN74ALS641ADWR equivalent, key selection considerations include its 20-pin SOIC footprint, 48 mA IOL capability (−1 version), ALS logic family timing and drive strength, and compatibility with 5-V TTL/CMOS bus systems requiring isolation and direction control.
Technical Context
The SN74ALS641ADWR implements a dual-rail 8-bit bidirectional transceiver architecture with independent DIR and OE controls: DIR selects data flow direction (A→B or B→A), while OE enables/disables all outputs into high-impedance state. Its ALS logic family delivers improved speed-power tradeoff over standard LS, with guaranteed tPHL ≤ 18 ns and tPLH ≤ 25 ns under 50-pF load conditions.
It features totem-pole outputs with specified VOL = 0.5 V at IOL = 24 mA (standard) and 0.5 V at IOL = 48 mA (−1 variant), VIH = 2 V, VIL = 0.8 V, and ICC = 33–47 mA depending on output state - confirming its role as a robust, discrete-level bus interface rather than a programmable or integrated controller.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Low-Power Schottky (ALS), compatible with TTL input thresholds and 5-V supply |
| Bus Width | Octal (8-bit) bidirectional data path with separate A and B port terminals |
| Output Drive | 48 mA low-level output current (IOL), enabling direct drive of multiple TTL loads without buffers |
| Propagation Delay | tPHL ≤ 18 ns, tPLH ≤ 25 ns (VCC = 4.5–5.5 V, CL = 50 pF), suitable for sub-20-MHz synchronous bus operation |
| Operating Temperature | 0°C to 70°C ambient range, qualified for commercial and industrial embedded system environments |
| Supply Voltage | 4.5 V to 5.5 V, with absolute max rating of 7 V - requires stable 5-V rail with bypassing |
| Input Thresholds | VIH = 2.0 V min, VIL = 0.8 V max - ensures reliable interfacing with standard TTL and CMOS logic |
Pinout & Package
SN74ALS641ADWR uses a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NIPDAU lead finish, and MSL Level-1 rating for unlimited reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | DIR (Direction Control) | Active-high signal determining data flow: DIR = L → B→A; DIR = H → A→B |
| 2, 18 | OE (Output Enable) | Active-low enable: OE = L → transceiver active; OE = H → all outputs high-Z for bus isolation |
| 3–10 | A1–A8 | Port A bidirectional I/O pins - connect to local data bus or microcontroller data lines |
| 11–18 | B1–B8 | Port B bidirectional I/O pins - connect to remote bus, peripheral, or memory subsystem |
| 9 | GND | Ground reference for logic and output drivers; requires low-impedance PCB connection |
| 20 | VCC | +5 V power supply; must be decoupled locally with 0.1 µF ceramic capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional Data Flow Control | Dedicated DIR input enables deterministic A↔B routing without external logic or software overhead |
| High-Drive Output Capability | 48 mA IOL supports fan-out to ≥10 standard TTL loads, reducing need for external buffers in dense bus designs |
| True Logic Function | Non-inverting data transfer preserves signal polarity across both directions - critical for address/data integrity |
| 3-State Bus Isolation | OE-controlled high-impedance outputs prevent bus contention during multi-master arbitration or power sequencing |
| ALS Speed-Power Optimization | Combines LS-compatible timing (≤25 ns) with lower ICC than AS variants, improving thermal margin in compact layouts |
Applications
| Microprocessor System Bus Interface | Industrial PLC Backplane Expansion |
|---|---|
Use Scenario: Interfacing an 8-bit microcontroller data bus to external memory or peripheral ICs across a shared backplane. IC Role / Device Role / Timing Role: Bidirectional data transceiver managing read/write cycles between CPU and off-chip devices with precise direction and enable timing. Use Value: Eliminates need for discrete directional logic and pull-up networks, reducing component count and PCB area while maintaining cycle-accurate bus handshaking. | Use Scenario: Extending I/O capacity in modular PLC racks where multiple CPU and I/O modules share a common parallel bus. IC Role / Device Role / Timing Role: Isolating and routing data between master controller and slave I/O modules using DIR/OE for slot-specific addressing and hot-swap safety. Use Value: Enables deterministic bus arbitration and fault containment - OE disables faulty modules without disrupting adjacent slots. |
| Legacy Instrumentation Data Link | Test Equipment Signal Routing |
Use Scenario: Connecting GPIB or IEEE-488-compatible controllers to custom analog front-end boards via parallel status/data lines. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled data conduit between legacy 5-V TTL instrumentation buses and modern digital subsystems. Use Value: Maintains signal integrity across mixed-voltage domains while supporting legacy protocol timing requirements (e.g., handshake strobes). | Use Scenario: Configurable signal path switching in automated test equipment (ATE) where DUT interfaces require dynamic bus reconfiguration. IC Role / Device Role / Timing Role: Reconfigurable 8-bit data channel enabling multiplexed stimulus/response routing under firmware control. Use Value: Reduces relay count and mechanical wear by replacing electromechanical switches with solid-state, low-latency bidirectional routing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS641AN | Same ALS logic, identical electrical specs, but in 20-pin PDIP (N) package - larger footprint, through-hole mount | Suitable for prototyping, legacy board repair, or through-hole production where SOIC reflow is unavailable | Select SN74ALS641AN when manual assembly, socketing, or thermal mass requirements favor DIP over SOIC. |
| SN74AS641DW | Faster propagation (tPHL ≤ 7.5 ns), higher IOL (64 mA), but increased ICC (up to 136 mA) and AS-family noise sensitivity | Better for high-speed timing-critical paths (e.g., video data latching), but demands stricter layout and decoupling | Choose SN74AS641DW only when sub-10-ns delay is mandatory and power/EMI budgets allow. |
Compared with SN74ALS641AN and SN74AS641DW, SN74ALS641ADWR provides optimal balance of speed, drive strength, and power efficiency in surface-mount form - making it preferred for volume-manufactured industrial control and instrumentation PCBs where reliability and thermal management are prioritized over peak frequency.
Availability
SN74ALS641ADWR is available at Aetrix Electronics and suitable for industrial PLC backplanes, microprocessor bus expansion, legacy instrumentation interfaces, and automated test equipment requiring stable component supply and long-term manufacturability.
Supply support for SN74ALS641ADWR 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 TTL and advanced logic families.
The SN74ALS641ADWR belongs to TI's legacy 74ALS logic portfolio, engineered specifically for robust, low-power bidirectional bus interfacing in commercial and industrial systems operating at 5 V.
FAQ
What is the maximum recommended output current for SN74ALS641ADWR?
The SN74ALS641ADWR is rated for a maximum low-level output current (IOL) of 48 mA per pin when operating within VCC = 4.75 V to 5.25 V - this is the −1 version specification confirmed in the SDAS300 datasheet. Exceeding this value risks VOL degradation or thermal overstress. The SN74ALS641ADWR must be used with appropriate PCB copper area and ambient derating in sustained high-current operation.
Does SN74ALS641ADWR support hot-swap or live insertion?
SN74ALS641ADWR is not explicitly qualified for hot-swap operation. While its 3-state outputs (via OE) provide bus isolation, the device lacks built-in bus-hold, power-on reset, or I/O clamp diodes required for safe live insertion. For hot-swap applications, external protection circuitry - such as series current-limiting resistors and TVS diodes - must be added, and OE should be held inactive until power rails stabilize. Always verify system-level stress limits before deployment.
Is SN74ALS641ADWR pin-compatible with SN74ALS642ADWR?
No, SN74ALS641ADWR is not pin-compatible with SN74ALS642ADWR. Although both are 20-pin SOIC octal transceivers, SN74ALS642A implements inverting logic (data inverted on transfer), resulting in different internal signal routing and incompatible functional behavior. Swapping them without redesigning control logic and verifying data polarity will cause system failure. They share package and pin count but not function or pin mapping.
What is the meaning of "ALS641A" in the SN74ALS641ADWR part marking?
The "ALS641A" portion of the SN74ALS641ADWR part marking identifies the base device type: ALS denotes Advanced Low-Power Schottky logic family, 641 indicates the octal bidirectional transceiver with true (non-inverting) logic function, and A signifies the improved revision over original 74641. This marking appears on the top surface of the SOIC package and matches TI's standardized logic family nomenclature used across datasheets and packaging documentation.
Can SN74ALS641ADWR operate reliably at 4.5 V supply voltage?
Yes, SN74ALS641ADWR is fully specified to operate at VCC = 4.5 V, as confirmed by its recommended operating conditions (4.5 V to 5.5 V) and electrical characteristics tables tested at 4.5 V. At this minimum voltage, parameters including VOL ≤ 0.5 V (at IOL = 24 mA), tPHL ≤ 18 ns, and VIH = 2.0 V remain guaranteed. System designers must ensure supply ripple stays within ±50 mV and use adequate local decoupling to maintain stability.
SN74ALS641ADWR 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
SN74ALS641ADWR FAQ
1.How can I place an order for SN74ALS641ADWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS641ADWR 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 SN74ALS641ADWR reliable?
The price and inventory of SN74ALS641ADWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS641ADWR is usually 5 days.
3.What payment methods are accepted for SN74ALS641ADWR?
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4.How is shipping managed for SN74ALS641ADWR?
SN74ALS641ADWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS641ADWR 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 SN74ALS641ADWR?
For technical support, including SN74ALS641ADWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS641ADWR requirements.
6.How does Aetrix verify that SN74ALS641ADWR is sourced from the original manufacturer or authorized distributors?
All SN74ALS641ADWR 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 SN74ALS641ADWR meets industry standards.
7.What is the process for return or replacement of SN74ALS641ADWR?
All SN74ALS641ADWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS641ADWR, 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 SN74ALS641ADWR part is unused and in its original packaging.
Return procedure for SN74ALS641ADWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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