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Texas Instruments SN74ALS641A-1DB
- Part No.:
- SN74ALS641A-1DB
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS641A-1DB.pdf
- Description:
- BUS XCVR SINGLE 8-CH OPEN COLLEC
- Quantity:
- Payment:
- Shipping:
Inventory:1,274
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Product details
Overview
SN74ALS641A-1DB from Texas Instruments is an octal bidirectional bus transceiver with true logic, 20-pin SOIC (DW) package, 48 mA low-level output drive, 0°C to 70°C operating range, and 3-state control via DIR/OE inputs-used in legacy industrial backplane and parallel bus isolation applications.
For engineers reviewing the SN74ALS641A-1DB datasheet, SN74ALS641A-1DB pinout, SN74ALS641A-1DB application, or SN74ALS641A-1DB equivalent, key selection criteria include IOL capability at 48 mA, propagation delays under 32 ns, 5 V TTL-compatible voltage thresholds, and compatibility with high-density 20-pin DIP/SOIC board layouts.
Technical Context
This device implements asynchronous bidirectional data flow between two 8-bit buses using separate direction (DIR) and output-enable (OE) controls. Its 3-state outputs support bus isolation when OE is high, and its true logic configuration routes A→B or B→A without inversion.
Designed for 5 V TTL systems, it features guaranteed 48 mA sink current only in the -1 version (VCC = 4.75–5.25 V), meets ALS family timing specs (tPLH/tPHL ≤ 32 ns), and operates within 0°C to 70°C ambient-targeting non-automotive, fixed-function digital interconnects.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Type | True (non-inverting) bidirectional bus transceiver |
| IOL (Low-Level Output) | 48 mA - enables direct drive of heavy TTL loads without external buffers |
| VCC Operating Range | 4.5 V to 5.5 V - compatible with standard 5 V power rails |
| Propagation Delay | ≤32 ns (tPLH/tPHL) - supports synchronous operation up to ~15 MHz bus rates |
| Operating Temperature | 0°C to 70°C - suitable for commercial/industrial indoor equipment |
| Input Voltage Thresholds | VIH = 2.0 V, VIL = 0.8 V - ensures robust noise margin in TTL environments |
| Output Voltage Levels | VOH ≥ 5.5 V, VOL ≤ 0.5 V - maintains full TTL logic swing under load |
Pinout & Package
SN74ALS641A-1DB uses a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm pitch, 2.65 mm max height, and JEDEC MS-013 compliant footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | DIR (Direction Control) | Active-high signal selecting A→B (DIR=H) or B→A (DIR=L); determines data flow path |
| 2, 18 | OE (Output Enable) | Active-low control enabling/disabling all 16 I/Os; OE=H forces high-impedance isolation |
| 3–10 | A1–A8 (Port A) | 8-bit bidirectional I/O port connected to local bus; driven or sensed depending on DIR state |
| 11–18 | B1–B8 (Port B) | 8-bit bidirectional I/O port connected to remote bus; complements A-port in transceiver operation |
| 9 | GND | Ground reference for all logic and output stages |
| 20 | VCC | +5 V supply powering internal logic and output drivers |
Key Features
| Feature | Design Value |
|---|---|
| High Sink Drive | 48 mA IOL supports direct interfacing with multiple TTL inputs or resistive loads |
| Asynchronous Bidirectionality | No clock required-data flows immediately upon DIR/OE assertion, simplifying glue logic design |
| Bus Isolation | Tri-state outputs disable both ports simultaneously, preventing bus contention during idle states |
| TTL-Compatible Interface | Meets standard 5 V TTL VIH/VIL and VOH/VOL specs, ensuring drop-in replacement in legacy systems |
| 20-Pin High-Density Packaging | SOIC (DW) footprint saves PCB area vs. 300-mil DIP while maintaining hand-solderability |
Applications
| Industrial Backplane Interconnect | Legacy Computer Memory Expansion |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing real-time A/B port arbitration without clock synchronization. Use Value: 48 mA drive strength eliminates need for external bus buffers; 32 ns max delay preserves timing margins in 8 MHz ISA-style cycles. | Use Scenario: Enabling hot-swappable RAM modules in early PC/AT architecture memory subsystems. IC Role / Device Role / Timing Role: Direction-controlled data path between motherboard and module-side memory banks. Use Value: True logic mapping preserves byte ordering; OE-controlled isolation prevents data corruption during module insertion/removal. |
| Test Equipment Bus Arbitration | Embedded Controller Peripheral Bridging |
Use Scenario: Sharing GPIB or IEEE-488 bus lines among multiple instrument controllers in automated test racks. IC Role / Device Role / Timing Role: Bidirectional level translator and contention guard between master and slave controller buses. Use Value: DIR-selectable flow direction allows dynamic reconfiguration; 0.5 V VOL ensures clean low-state recognition across noisy lab environments. | Use Scenario: Connecting microcontroller GPIO banks to external peripherals (ADCs, DACs, displays) requiring isolated 8-bit parallel interfaces. IC Role / Device Role / Timing Role: Synchronous data shuttle between MCU port and peripheral data bus under software DIR control. Use Value: 20-pin SOIC fits compact embedded boards; 0°C–70°C rating matches industrial MCU operating envelope. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS641A-1DWR | Same die, SOIC (DW) tape-and-reel packaging (2000 pcs), identical electrical specs and pinout | Identical function; optimized for automated SMT assembly vs. manual DB (tube) handling | Select for volume production with pick-and-place placement |
| SN74ALS642A-1N | Inverting logic (vs. true), PDIP (N) package, same 48 mA IOL and timing specs | Requires logic inversion in system firmware or upstream logic; suited for designs where inverted bus polarity is acceptable | Choose only if system-level signal polarity accommodates inversion |
Compared with SN74ALS641A-1DB, SN74ALS641A-1DWR offers identical performance in automated assembly format, while SN74ALS642A-1N provides matching drive and speed but mandates signal inversion-making the former a layout-compatible upgrade and the latter a functional alternative only when polarity can be managed at system level.
Availability
SN74ALS641A-1DB is available at Aetrix Electronics and suitable for industrial backplane interconnect, legacy computer memory expansion, and test equipment bus arbitration requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74ALS641A-1DB 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 SN74ALS641A-1DB belongs to TI's 74ALS advanced low-power Schottky logic family, designed specifically for high-speed, low-noise, 5 V TTL-compatible digital interconnect in space-constrained commercial and industrial systems.
FAQ
What is the maximum sink current supported by SN74ALS641A-1DB?
The SN74ALS641A-1DB supports a guaranteed low-level output current (IOL) of 48 mA per pin when VCC is between 4.75 V and 5.25 V. This rating applies exclusively to the "-1" version and exceeds the 24 mA spec of the standard SN74ALS641A, enabling direct drive of heavier TTL loads without external buffering. The value is validated per TI's SDAS300 datasheet Section "Recommended Operating Conditions".
Does SN74ALS641A-1DB support inverting logic functionality?
No, SN74ALS641A-1DB implements true (non-inverting) logic. Data passes unchanged from A to B or B to A depending on the DIR input state. For inverting behavior, TI offers the functionally similar SN74ALS642A-1 series, which performs identical bidirectional transceiving but with complemented output polarity. The distinction is explicitly defined in the device family description on page 1 of the SDAS300 datasheet.
What package type is used for SN74ALS641A-1DB?
SN74ALS641A-1DB uses a 20-pin SOIC (DW) package-plastic small-outline integrated circuit with 1.27 mm lead pitch, 7.5 mm × 12.8 mm body dimensions, and 2.65 mm maximum height. This is confirmed in TI's Package Option Addendum and the DW0020A package outline drawing, and distinguishes it from PDIP (N) and SOP (NS) variants of the same part number.
Can SN74ALS641A-1DB operate outside the 0°C to 70°C temperature range?
No-SN74ALS641A-1DB is characterized and specified only for operation from 0°C to 70°C ambient temperature. Its absolute maximum ratings allow storage from −65°C to 150°C, but functional operation outside the recommended range is not guaranteed. This limitation is stated in the "Recommended Operating Conditions" table on page 3 of the SDAS300 datasheet and applies to all ALS641A-1 variants.
How does the DIR and OE control logic work in SN74ALS641A-1DB?
In SN74ALS641A-1DB, DIR selects data direction (DIR = L → B-to-A; DIR = H → A-to-B), while OE enables or disables all I/Os (OE = L → active; OE = H → high-impedance isolation). Both controls are asynchronous and independent-OE overrides DIR when asserted high, forcing bus isolation regardless of direction setting. This dual-control scheme is documented in the Function Table on page 1 of the SDAS300 datasheet.
SN74ALS641A-1DB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- 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:
- 100µA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74ALS641A-1DB FAQ
1.How can I place an order for SN74ALS641A-1DB through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS641A-1DB 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-1DB reliable?
The price and inventory of SN74ALS641A-1DB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS641A-1DB is usually 5 days.
3.What payment methods are accepted for SN74ALS641A-1DB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS641A-1DB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS641A-1DB?
SN74ALS641A-1DB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS641A-1DB 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-1DB?
For technical support, including SN74ALS641A-1DB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS641A-1DB requirements.
6.How does Aetrix verify that SN74ALS641A-1DB is sourced from the original manufacturer or authorized distributors?
All SN74ALS641A-1DB 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-1DB meets industry standards.
7.What is the process for return or replacement of SN74ALS641A-1DB?
All SN74ALS641A-1DB units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS641A-1DB, 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-1DB part is unused and in its original packaging.
Return procedure for SN74ALS641A-1DB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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