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Texas Instruments SN74AS641DWR
- Part No.:
- SN74AS641DWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74AS641DWR.pdf
- Description:
- IC TXRX INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,210
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Product details
Overview
SN74AS641DWR 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, 5 V supply operation, 64 mA low-level output drive, and operates from 0°C to 70°C - used in legacy industrial backplane and memory interface systems.
For engineers reviewing the SN74AS641DWR datasheet, SN74AS641DWR pinout, SN74AS641DWR application, or SN74AS641DWR equivalent, key selection criteria include direction-control (DIR) and output-enable (OE) timing, 3-state isolation behavior, high-current drive capability, and compatibility with TTL/LS logic families in bus-hold or hot-swap-adjacent designs.
Technical Context
This device implements dual 8-bit bidirectional data paths controlled by DIR (data flow direction) and OE (3-state enable). Its architecture supports simultaneous A→B or B→A transmission without internal latching, relying on external control sequencing.
It uses bipolar Schottky (AS) technology for fast propagation (tPHL as low as 1 ns), high noise immunity (VIK = −1.2 V), and robust drive strength (IOL = 64 mA at VCC = 4.5–5.5 V), distinguishing it from ALS variants with lower current and slower switching.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74AS - high-speed bipolar Schottky, compatible with TTL input thresholds and LS output loading. |
| Supply Voltage | 4.5 V to 5.5 V - requires stable 5 V rail; not 3.3 V tolerant. |
| Low-Level Output Current | 64 mA - enables direct driving of multiple TTL loads or termination resistors without buffers. |
| Propagation Delay | tPHL = 1–7.5 ns - supports >50 MHz bus toggle rates under 50 pF load. |
| Input Clamp Voltage | VIK = −1.2 V - provides ESD protection and negative transient immunity on I/O pins. |
| Operating Temperature | 0°C to 70°C - commercial-grade rating; not extended or automotive qualified. |
| Output Enable Time | tPZL/tPLZ ≤ 9 ns - ensures rapid bus release during dynamic arbitration or multiplexing. |
Pinout & Package
SN74AS641DWR is housed in a 20-pin SOIC (DW) package, 7.5 mm wide, 12.83 mm long, 2.65 mm max height, with 1.27 mm pitch gull-wing leads. Pin 1 is marked by a beveled corner or notch on the top surface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control: LOW = B→A transfer, HIGH = A→B transfer. |
| 2 | A1 | Terminal 1 of A-side 8-bit bus - bidirectional I/O with 3-state control. |
| 3–9 | A2–A8 | A-side bus terminals 2 through 8 - all identical bidirectional I/Os. |
| 10 | GND | Ground reference for logic and power return path. |
| 11–18 | B1–B8 | B-side bus terminals 1 through 8 - matched bidirectional I/Os with same timing as A side. |
| 19 | VCC | +5 V supply - must be decoupled locally due to high ICC peaks (up to 136 mA). |
| 20 | OE | Output enable: LOW = active transceiver, HIGH = 3-state isolation of both A and B buses. |
Key Features
| Feature | Design Value |
|---|---|
| True Logic Configuration | Non-inverting data path eliminates need for external inversion in A↔B mirroring applications. |
| 64 mA Sink Capability | Drives heavy capacitive loads or multiple TTL inputs directly - reduces component count in legacy bus interfaces. |
| Sub-10 ns Enable/Disable | Enables precise time-multiplexed bus sharing without glitches or contention windows. |
| −1.2 V Input Clamp | Protects against negative undershoot during cable disconnection or hot-plug events in industrial backplanes. |
| SOIC (DW) Packaging | Surface-mount footprint compatible with automated assembly and reflow profiles per JEDEC Level-1. |
Applications
| Industrial Backplane Interface | Legacy Memory Bus Expansion |
|---|---|
Use Scenario: Interfacing CPU local bus to peripheral expansion slots in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Bidirectional data bridge enabling read/write cycles across isolated board segments with DIR-controlled flow direction. Use Value: 64 mA drive sustains signal integrity over 15 cm PCB traces loaded with 10+ TTL inputs; tPHL < 7.5 ns meets 20 MHz bus clock timing budgets. | Use Scenario: Extending 8-bit data bus between microcontroller and external SRAM or EPROM in embedded instrumentation. IC Role / Device Role / Timing Role: Isolates memory address/data lines during reset or standby using OE, preventing bus contention during power-up sequencing. Use Value: 3-state isolation leakage < 0.1 µA ensures no DC loading on inactive memory chips; VIH/VIL thresholds match standard 5 V TTL memory devices. |
| Test Equipment Data Mux | Modular I/O Subsystem |
Use Scenario: Routing sensor data from multiple analog front-ends to a central ADC/DSP in automated test systems. IC Role / Device Role / Timing Role: Directionally configurable channel selector - DIR toggled per measurement cycle to alternate between acquisition and calibration paths. Use Value: Propagation delay variation < 2 ns across all 8 channels ensures synchronized sampling window alignment across multi-channel capture. | Use Scenario: Enabling hot-swappable I/O modules in modular automation racks where bus segments are dynamically enabled/disabled. IC Role / Device Role / Timing Role: Bus isolator activated via system controller's OE signal to decouple faulty modules without resetting entire backplane. Use Value: Fast disable time (tPLZ ≤ 9 ns) prevents metastability or latch-up during module insertion/removal under live power conditions. |
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 | ALS family: lower IOL (24 mA), slower tPHL (3–18 ns), higher noise margin but reduced drive. | Suitable for low-power, noise-sensitive environments where bus capacitance < 30 pF and speed < 10 MHz. | Select when thermal budget or static power limits preclude AS-family ICC peaks (136 mA). |
| SN74AS641N | Identical electrical specs but in 20-pin PDIP (N) package - through-hole, 300-mil width, no reflow compatibility. | Used in prototyping, repair, or legacy through-hole production where SOIC placement is unavailable. | Choose only for hand-soldered evaluation or replacement in existing DIP-based systems; not for new SMT designs. |
Compared with SN74ALS641ADWR, SN74AS641DWR delivers 2.7× higher sink current and ~5× faster turn-off, making it essential for high-speed, high-fanout bus buffering; versus SN74AS641N, it offers identical functionality in a space-optimized, automated-assembly-ready SOIC format.
Availability
SN74AS641DWR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy memory bus expansion, test equipment data muxing, modular I/O subsystems, and programmable logic controller (PLC) designs requiring stable component supply across long-lifecycle programs.
Supply support for SN74AS641DWR 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 ICs for industrial, automotive, and communications markets.
The SN74AS641DWR belongs to TI's 74AS logic family - engineered for high-speed, high-drive 5 V TTL-compatible bus interfacing in mission-critical industrial control and instrumentation systems.
FAQ
What is the maximum recommended supply voltage for SN74AS641DWR?
The absolute maximum supply voltage for SN74AS641DWR is 7 V, but the recommended operating range is strictly 4.5 V to 5.5 V. Operation above 5.5 V risks permanent damage and violates TI's recommended conditions; sustained use at 7 V is prohibited even briefly. SN74AS641DWR must be powered from a well-regulated 5 V source with adequate decoupling to handle peak ICC of 136 mA.
Does SN74AS641DWR support 3.3 V logic levels?
No, SN74AS641DWR does not support 3.3 V logic levels. Its input thresholds (VIH = 2 V min, VIL = 0.8 V max) and output swing (VOH ≥ 5.5 V at IOL = 0) are specified only for 5 V operation. Driving SN74AS641DWR inputs from 3.3 V sources may result in marginal or non-functional high-level recognition; likewise, connecting its outputs to 3.3 V CMOS inputs risks overvoltage damage. SN74AS641DWR requires full 5 V signaling throughout the system.
How does the DIR pin control data flow direction in SN74AS641DWR?
In SN74AS641DWR, the DIR pin determines real-time data path direction: when DIR = LOW, data flows from the B bus to the A bus; when DIR = HIGH, data flows from the A bus to the B bus. This is a synchronous, level-sensitive control - no clock required. The function is valid only when OE = LOW; if OE = HIGH, both buses are placed in high-impedance state regardless of DIR state. Timing parameters like tPLH(DIR→A/B) are guaranteed at 5–22 ns.
Can SN74AS641DWR replace SN74ALS641A in an existing design?
SN74AS641DWR can replace SN74ALS641A electrically and pin-for-pin, but thermal and timing validation is required. While both share identical pinout, truth table, and 5 V operation, SN74AS641DWR draws significantly higher ICC (up to 136 mA vs. 47 mA) and switches faster (tPHL down to 1 ns vs. 3 ns). Ensure PCB layout supports increased power dissipation and that downstream setup/hold margins accommodate reduced propagation delay skew. SN74AS641DWR is not a drop-in replacement without system-level verification.
What is the meaning of the "DWR" suffix in SN74AS641DWR?
The "DWR" suffix in SN74AS641DWR denotes Texas Instruments' packaging and packaging format: "DW" = SOIC (Small-Outline Integrated Circuit) package with 20 pins and 1.27 mm lead pitch; "R" = supplied in large tape-and-reel format (2000 units per reel). This distinguishes it from "DW" (tube, 25 pcs), "N" (PDIP tube), or "NSR" (SOP tape-and-reel). SN74AS641DWR is RoHS-compliant, NIPDAU lead finish, and JEDEC Level-1 moisture sensitivity rated.
SN74AS641DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- -, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74AS641DWR FAQ
1.How can I place an order for SN74AS641DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS641DWR 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 SN74AS641DWR reliable?
The price and inventory of SN74AS641DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS641DWR is usually 5 days.
3.What payment methods are accepted for SN74AS641DWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS641DWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS641DWR?
SN74AS641DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS641DWR 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 SN74AS641DWR?
For technical support, including SN74AS641DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS641DWR requirements.
6.How does Aetrix verify that SN74AS641DWR is sourced from the original manufacturer or authorized distributors?
All SN74AS641DWR 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 SN74AS641DWR meets industry standards.
7.What is the process for return or replacement of SN74AS641DWR?
All SN74AS641DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS641DWR, 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 SN74AS641DWR part is unused and in its original packaging.
Return procedure for SN74AS641DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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