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Texas Instruments SN74ALS641AN
- Part No.:
- SN74ALS641AN
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ALS641AN.pdf
- Description:
- IC TRANSCEIVER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,629
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Product details
Overview
SN74ALS641AN from Texas Instruments is an octal bidirectional bus transceiver in a 20-pin PDIP package, implementing true (non-inverting) logic for asynchronous two-way data transfer between A and B buses. It features direction control (DIR), output enable (OE), 48 mA low-level output drive (IOL), 5 V supply operation, and 0°C to 70°C temperature range-used in legacy industrial backplane and board-to-board communication interfaces.
For engineers reviewing the SN74ALS641AN datasheet, SN74ALS641AN pinout, SN74ALS641AN application, or SN74ALS641AN equivalent, key selection criteria include its 20-pin DIP mechanical compatibility, -1 version's 48 mA IOL rating, DIR/OE dual-control architecture, ALS family propagation delays (tPLH/tPHL ≤ 32 ns), and isolation capability during OE high.
Technical Context
The SN74ALS641AN implements a TTL-compatible octal transceiver with independent DIR and OE inputs enabling full bus isolation or directional data flow. Its internal circuitry supports simultaneous A→B or B→A transmission based on DIR state, while OE disables all outputs to high-impedance.
It belongs to the 74ALS logic family, delivering improved speed-power trade-offs over standard 74LS, with guaranteed 48 mA sink current per output at VCC = 4.75–5.25 V and VOL ≤ 0.5 V under load-critical for driving terminated parallel buses in legacy computing and instrumentation systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74ALS - provides 2× speed vs 74LS with comparable power, suited for legacy 5 V systems requiring robust noise margin |
| Supply Voltage | 4.5 V to 5.5 V - operates reliably across standard 5 V rail tolerances without external regulation |
| Output Drive (IOL) | 48 mA - enables direct interface to multiple TTL loads or terminated 50 Ω lines without buffer amplification |
| Propagation Delay | tPLH/tPHL ≤ 32 ns - ensures sub-32 ns latency for bidirectional bus arbitration in real-time control applications |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded systems including industrial controllers and test equipment |
| Package Type | PDIP-20 (N) - 300-mil through-hole format compatible with wave soldering and manual prototyping |
| Input Logic Levels | VIL = 0.8 V, VIH = 2.0 V - TTL-compatible thresholds ensure interoperability with 74xx, 74LS, and 74F families |
Pinout & Package
SN74ALS641AN uses a 20-pin plastic dual in-line package (PDIP-N), 300-mil width, 0.100″ lead pitch, with standard DIP footprint and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control input: LOW enables B→A data flow; HIGH enables A→B data flow |
| 2 | A1 | Bus A side I/O terminal 1 - bidirectional signal path tied to A bus |
| 3–9 | A2–A8 | Bus A side I/O terminals 2–8 - collectively form 8-bit A bus interface |
| 10 | GND | Ground reference - common return for all signals and power |
| 11–18 | B1–B8 | Bus B side I/O terminals 1–8 - collectively form 8-bit B bus interface |
| 19 | VCC | Positive supply - 4.5–5.5 V DC required for operation |
| 20 | OE | Output enable input - LOW enables transceiver; HIGH places all A/B pins in high-impedance state |
Key Features
| Feature | Design Value |
|---|---|
| True (non-inverting) logic | Preserves signal polarity across A↔B paths - eliminates need for external inversion in symmetric bus architectures |
| 48 mA output sink capability | Drives up to 12 standard TTL loads or 50 Ω transmission lines - reduces need for external drivers in backplane designs |
| Independent DIR and OE controls | Enables flexible bus management: DIR sets direction while OE provides global isolation - critical for hot-swap and fault containment |
| ALS family speed-power balance | Delivers 32 ns max propagation delay at ~40 mA ICC (outputs low) - optimal for cost-sensitive 5 V systems where AS speed isn't required |
| High-impedance isolation mode | OE = HIGH disconnects both A and B buses electrically - prevents contention during system reset or configuration changes |
Applications
| Industrial Backplane Interface | Legacy Computer Memory Expansion |
|---|---|
Use Scenario: Interfacing microprocessor local bus to peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional data bridge between CPU address/data bus and modular I/O cards, controlled by system DIR and OE signals. Use Value: 48 mA drive ensures reliable signaling across 15 cm backplane traces; DIR/OE separation allows dynamic bus arbitration without software overhead. | Use Scenario: Adding RAM or EPROM modules to vintage 8-bit computer motherboards using parallel bus architecture. IC Role / Device Role / Timing Role: Octal transceiver isolating memory module data lines from main system bus during read/write cycles. Use Value: True logic preserves data integrity; 32 ns propagation delay meets 4 MHz bus timing budgets without wait states. |
| Test Equipment Signal Routing | Industrial Data Acquisition Front-End |
Use Scenario: Switching analog-to-digital converter outputs between multiple processing channels in automated test systems. IC Role / Device Role / Timing Role: Bus transceiver enabling multiplexed data routing from ADCs to FPGA-based capture logic under firmware control. Use Value: High-impedance isolation during OE high prevents channel crosstalk; PDIP package simplifies field-replaceable module design. | Use Scenario: Isolating sensor signal conditioning circuits from central controller bus in factory-floor monitoring units. IC Role / Device Role / Timing Role: Direction-controlled interface between isolated analog front-end and microcontroller data bus. Use Value: DIR-driven A↔B switching supports both sensor readout and calibration command injection; 0°C–70°C rating matches industrial ambient requirements. |
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 | SOIC-20 surface-mount package; identical electrical specs and pinout; same 48 mA IOL, 32 ns tPHL | Requires PCB redesign for SMT assembly; not interchangeable in through-hole sockets | Select for space-constrained or automated production environments where reflow soldering is available |
| SN74AS641N | Faster propagation (7.5 ns tPHL), higher IOL (64 mA), but increased ICC (up to 136 mA); different VIH/VIL thresholds | Higher power consumption and stricter layout requirements due to faster edges; may require termination tuning | Select only when sub-10 ns latency is mandatory and thermal/power budget permits AS family operation |
Compared with SN74ALS641ADWR, the SN74ALS641AN offers identical logic behavior and performance in a through-hole package for serviceability and prototyping; compared with SN74AS641N, it trades speed for lower power and broader voltage tolerance-making it preferable for stable, cost-optimized 5 V industrial designs.
Availability
SN74ALS641AN is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy computer expansion systems, and test equipment signal routing requiring stable component supply and long-term obsolescence support.
Supply support for SN74ALS641AN 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ALS641AN belongs to TI's legacy 74ALS logic product line, designed specifically for high-reliability, 5 V parallel bus interfacing in industrial control and instrumentation systems where pin compatibility and long-term availability are critical.
FAQ
What is the maximum output sink current specification for SN74ALS641AN?
The SN74ALS641AN is rated for 48 mA low-level output current (IOL) per pin when VCC is between 4.75 V and 5.25 V. This value is specified in the "recommended operating conditions" table of the SDAS300 datasheet and applies only to the -1 version designation, which SN74ALS641AN carries. It ensures robust drive capability into heavily loaded or terminated 5 V buses without external buffering.
Does SN74ALS641AN support bidirectional data flow without external logic?
Yes, SN74ALS641AN natively supports bidirectional data flow using its dedicated DIR (direction) and OE (output enable) inputs. When OE is LOW, setting DIR LOW routes data from B bus to A bus, and setting DIR HIGH routes data from A bus to B bus-all without external gates or latches. This integrated control makes SN74ALS641AN ideal for compact bus arbitration in space-constrained industrial modules.
Is SN74ALS641AN pin-compatible with SN74ALS642AN?
No, SN74ALS641AN is not pin-compatible with SN74ALS642AN. While both are 20-pin octal transceivers in PDIP packages, SN74ALS642AN implements inverting logic (complemented data path), resulting in different internal signal routing and incompatible functional behavior-even though pin numbering and physical layout match. Substituting them requires logic inversion elsewhere in the system.
What is the operating temperature range certified for SN74ALS641AN?
SN74ALS641AN is characterized and guaranteed to operate across 0°C to 70°C ambient temperature, as confirmed in the "recommended operating conditions" section of the SDAS300 datasheet. This commercial-grade range aligns with typical industrial control cabinets and laboratory test equipment enclosures, and excludes extended temperature variants like −40°C to 85°C.
Can SN74ALS641AN be used with 3.3 V logic systems?
No, SN74ALS641AN is not designed for 3.3 V operation. Its absolute maximum VCC is 7 V, but recommended operation is strictly 4.5–5.5 V. Input thresholds (VIL = 0.8 V, VIH = 2.0 V) and output levels (VOH ≥ 5.5 V) are TTL/5 V-centric. Interfacing with 3.3 V systems requires level-shifting circuitry or a 3.3 V–compatible transceiver such as SN74LVC8T245.
SN74ALS641AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74ALS641AN FAQ
1.How can I place an order for SN74ALS641AN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS641AN 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 SN74ALS641AN reliable?
The price and inventory of SN74ALS641AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS641AN is usually 5 days.
3.What payment methods are accepted for SN74ALS641AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS641AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS641AN?
SN74ALS641AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS641AN 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 SN74ALS641AN?
For technical support, including SN74ALS641AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS641AN requirements.
6.How does Aetrix verify that SN74ALS641AN is sourced from the original manufacturer or authorized distributors?
All SN74ALS641AN 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 SN74ALS641AN meets industry standards.
7.What is the process for return or replacement of SN74ALS641AN?
All SN74ALS641AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS641AN, 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 SN74ALS641AN part is unused and in its original packaging.
Return procedure for SN74ALS641AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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