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Texas Instruments SN74ALS641ADW
- Part No.:
- SN74ALS641ADW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS641ADW.pdf
- Description:
- IC TXRX INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,146
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Product details
Overview
SN74ALS641ADW from Texas Instruments is an octal bidirectional bus transceiver in a 20-pin SOIC (DW) package, designed for asynchronous two-way data communication between A and B buses. It features true logic polarity, direction control (DIR), output enable (OE), and supports 24 mA low-level output current with 5 V supply operation across 0°C to 70°C.
For engineers reviewing the SN74ALS641ADW datasheet, SN74ALS641ADW pinout, SN74ALS641ADW application, or SN74ALS641ADW equivalent, key selection considerations include its 20-pin SOIC footprint, 24 mA IOL drive capability, DIR/OE dual-control architecture, and compatibility with legacy TTL/ALS bus systems requiring isolated bidirectional data flow.
Technical Context
The SN74ALS641ADW implements a dual-control 3-state bus transceiver architecture where DIR selects data direction (A→B or B→A) and OE enables/disables all outputs simultaneously. Its internal circuitry uses bipolar ALS (Advanced Low-Power Schottky) technology, delivering TTL-compatible voltage thresholds (VIH = 2 V, VIL = 0.8 V) and guaranteed 24 mA sink capability at VCC = 4.5–5.5 V.
Propagation delays are specified under 50 pF load and 680 Ω termination: tPLH/tPHL from A/B to opposite bus range 3–25 ns, while DIR- and OE-controlled transitions fall within 5–32 ns. The device operates strictly in the commercial temperature range (0°C to 70°C) and requires no external biasing or pull-ups for standard bus interfacing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS (Advanced Low-Power Schottky) - ensures TTL compatibility with reduced power vs standard LS. |
| Bus Width | Octal (8-bit) bidirectional - supports parallel data transfer across two independent 8-bit buses. |
| IOL (max) | 24 mA per output - sufficient to drive standard TTL loads without external buffers. |
| VCC Range | 4.5 V to 5.5 V - compatible with regulated 5 V supply rails in industrial and computing systems. |
| Propagation Delay | 3–25 ns - enables reliable operation up to ~20 MHz bus rates under typical loading. |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade embedded and peripheral interface applications. |
| Input Thresholds | VIH = 2 V, VIL = 0.8 V - matches standard TTL logic levels for seamless integration. |
Pinout & Package
SN74ALS641ADW is housed in a 20-pin SOIC (DW) package measuring 12.8 mm × 7.5 mm × 2.65 mm max height, with 1.27 mm pitch, gull-wing leads, and JEDEC MS-013 compliant outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | DIR | Direction control input: LOW enables B→A data flow; HIGH enables A→B data flow. |
| 2, 18 | OE | Output enable input: LOW activates transceiver; HIGH places all A/B I/Os in high-impedance state. |
| 3–10 | A1–A8 | Port A bidirectional I/Os - connect to first data bus segment (e.g., CPU/local bus). |
| 11–18 | B1–B8 | Port B bidirectional I/Os - connect to second data bus segment (e.g., peripheral/memory bus). |
| 9 | GND | Ground reference for all logic and I/O circuits. |
| 20 | VCC | Positive supply input (4.5–5.5 V) powering internal logic and output drivers. |
Key Features
| Feature | Design Value |
|---|---|
| True Logic Polarity | Non-inverting data path preserves signal phase integrity during bidirectional transfer. |
| Dual Independent Control | Separate DIR and OE inputs allow flexible bus arbitration - direction and enable can be managed independently. |
| TTL-Compatible Interface | Meets standard TTL VIH/VIL and VOH/VOL specs, enabling drop-in replacement in legacy 74-series designs. |
| High-Drive Output Capability | 24 mA IOL supports direct connection to multiple TTL inputs or moderate capacitive bus loads. |
| 3-State Bus Isolation | When OE = HIGH, both A and B ports enter high-Z state, preventing bus contention during idle or multi-master operation. |
Applications
| Microprocessor System Bus Interface | Industrial PLC Backplane Communication |
|---|---|
Use Scenario: Interfacing an 8-bit microprocessor data bus to external memory or I/O peripherals with shared address/data lines. IC Role / Device Role / Timing Role: Bidirectional data buffer managing time-multiplexed bus transfers under CPU control via DIR and OE signals. Use Value: Enables clean separation of read/write cycles without external glue logic; 24 mA drive ensures robust signal integrity on loaded PCB traces. | Use Scenario: Connecting modular I/O cards to a central controller backplane in programmable logic controllers. IC Role / Device Role / Timing Role: Isolating and routing parallel status/command data between controller and field modules using common backplane wiring. Use Value: High-Z isolation prevents cross-talk during hot-swap or module reconfiguration; ALS speed supports real-time scan cycle timing. |
| Legacy Computer Peripheral Expansion | Test Equipment Data Acquisition Interface |
Use Scenario: Adding ISA-style expansion slots to retro-computing or embedded x86 platforms requiring bidirectional data bridging. IC Role / Device Role / Timing Role: Transceiver mediating data flow between host bus and add-on card, synchronized to system clock edges via DIR timing. Use Value: True logic behavior maintains original system timing margins; SOIC package fits space-constrained board layouts. | Use Scenario: Routing sensor data from analog-to-digital converter modules to a central FPGA or microcontroller in benchtop test instruments. IC Role / Device Role / Timing Role: Level-shifting and bus-isolating parallel digital outputs from ADCs before multiplexing into main processing unit. Use Value: Guaranteed 0°C–70°C operation ensures reliability during extended lab use; 5 V tolerance accommodates varied supply domains. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS641ADWR | Same die and electrical specs; tape-and-reel packaging (2000 pcs) vs tube (SN74ALS641ADW is obsolete, DWR is active). | Identical functional use; preferred for automated SMT assembly due to reel format and active status. | Select SN74ALS641ADWR for new designs requiring volume production support and RoHS-compliant NIPDAU finish. |
| SN74ALS642ADW | Inverting logic polarity (vs true logic in SN74ALS641ADW); otherwise identical pinout, timing, and drive specs. | Requires logic inversion in upstream/downstream circuitry; suitable only where inverted data path is acceptable or compensated. | Choose SN74ALS642ADW only when system-level signal polarity allows inversion - not a drop-in replacement. |
Compared with SN74ALS641ADW, SN74ALS641ADWR offers identical functionality with modern packaging and lifecycle support, while SN74ALS642ADW provides the same physical interface but inverted data transfer - making the former a direct upgrade path and the latter a conditional alternative requiring design-level verification of polarity requirements.
Availability
SN74ALS641ADW is available at Aetrix Electronics and suitable for microprocessor bus interfacing, industrial backplane communication, legacy computer expansion, test equipment data acquisition, and embedded control systems requiring stable component supply and long-term sourcing continuity.
Supply support for SN74ALS641ADW 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 SN74ALS641ADW belongs to TI's 74ALS logic series, engineered for high-speed, low-power bidirectional bus interfacing in commercial-grade computing and industrial control systems where reliability and TTL compatibility are critical.
FAQ
What is the operating temperature range for SN74ALS641ADW?
The SN74ALS641ADW is characterized for operation from 0°C to 70°C - the commercial temperature range. This specification is confirmed in the recommended operating conditions table of the SDAS300 datasheet, and applies to all SN74ALS641A variants including the SN74ALS641ADW. Operation outside this range may result in undefined performance or reliability degradation.
Does SN74ALS641ADW support 3.3 V operation?
No, SN74ALS641ADW does not support 3.3 V operation. Its recommended VCC range is strictly 4.5 V to 5.5 V, and absolute maximum rating is 7 V. The device uses ALS bipolar technology optimized for 5 V TTL systems; applying 3.3 V will result in insufficient noise margin, unreliable switching, and potential failure to meet VIH/VIL thresholds. For 3.3 V bus interfaces, consider LVCMOS or LVT logic families instead.
Is SN74ALS641ADW pin-compatible with SN74ALS642ADW?
Yes, SN74ALS641ADW and SN74ALS642ADW share identical pinout, package (DW), and terminal functions - including DIR, OE, A1–A8, B1–B8, VCC, and GND. However, they differ in logic polarity: SN74ALS641ADW is true (non-inverting), while SN74ALS642ADW is inverting. Substitution requires verification that signal inversion is acceptable or compensated elsewhere in the design.
What is the maximum output sink current (IOL) for SN74ALS641ADW?
The maximum guaranteed low-level output current (IOL) for SN74ALS641ADW is 24 mA per output, specified at VCC = 4.5 V and TA = 0°C to 70°C. This value is documented in the "recommended operating conditions" table of the SDAS300 datasheet. Note that the -1 version (e.g., SN74ALS641A-1DWR) supports 48 mA, but SN74ALS641ADW is the standard version with 24 mA rating.
Can SN74ALS641ADW be used in place of SN74AS641DW?
SN74ALS641ADW and SN74AS641DW are not direct substitutes. While both are 20-pin SOIC octal transceivers with true logic, SN74AS641DW is an Advanced Schottky device with higher speed (tPHL down to 1 ns) and greater drive (64 mA IOL), but also higher ICC (up to 136 mA). SN74ALS641ADW offers lower power and better noise immunity at the cost of speed - substitution requires validation of timing margins and power budget in the target application.
SN74ALS641ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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
SN74ALS641ADW FAQ
1.How can I place an order for SN74ALS641ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS641ADW 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 SN74ALS641ADW reliable?
The price and inventory of SN74ALS641ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS641ADW is usually 5 days.
3.What payment methods are accepted for SN74ALS641ADW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS641ADW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS641ADW?
SN74ALS641ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS641ADW 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 SN74ALS641ADW?
For technical support, including SN74ALS641ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS641ADW requirements.
6.How does Aetrix verify that SN74ALS641ADW is sourced from the original manufacturer or authorized distributors?
All SN74ALS641ADW 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 SN74ALS641ADW meets industry standards.
7.What is the process for return or replacement of SN74ALS641ADW?
All SN74ALS641ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS641ADW, 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 SN74ALS641ADW part is unused and in its original packaging.
Return procedure for SN74ALS641ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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