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Texas Instruments SN74ALS640BNSRG4
- Part No.:
- SN74ALS640BNSRG4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS640BNSRG4.pdf
- Description:
- IC TRANSCEIVER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,105
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Product details
Overview
SN74ALS640BNSRG4 from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in TTL-compatible systems. It features inverting logic, 20-pin PDIP (N) package, 0°C to 70°C operating range, 12 mA low-level output current, and direction-control (DIR) and output-enable (OE) inputs for bus isolation.
For engineers reviewing the SN74ALS640BNSRG4 datasheet, SN74ALS640BNSRG4 pinout, SN74ALS640BNSRG4 application, or SN74ALS640BNSRG4 equivalent, this page delivers verified electrical specs, functional timing behavior, package mapping, real-world use cases, and validated alternative parts for industrial control, legacy system repair, and backplane interface design.
Technical Context
This device implements a dual-bus bidirectional transceiver architecture with active-low 3-state control: OE disables all outputs to high-impedance, while DIR selects data flow direction (A→B when high, B→A when low). Its inverting logic means output states are inverted relative to input states during enabled transmission.
It operates strictly within TTL voltage thresholds (VIL ≤ 0.8 V, VIH ≥ 2 V), supports 5 V ±10% supply, and delivers guaranteed VOL ≤ 0.4 V at IOL = 12 mA - enabling reliable interfacing with standard 74LS/ALS loads without level-shifting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Octal bidirectional bus transceiver with 3-state outputs and inverting logic |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V TTL power rails |
| Operating Temperature | 0°C to 70°C - commercial-grade rating for non-military embedded systems |
| Output Drive | IOL = 12 mA (min) - sufficient to drive 10 LS-TTL loads or 20 ALS loads |
| Propagation Delay | tPLH/tPHL ≤ 11 ns - supports synchronous bus operation up to ~45 MHz in short traces |
| Enable Timing | tPZH/tPLZ ≤ 24 ns - ensures clean bus isolation during state transitions |
| Package | 20-pin plastic DIP (N) - through-hole mounting, 300-mil width, RoHS-compliant lead finish |
Pinout & Package
SN74ALS640BNSRG4 uses a 20-pin plastic dual in-line package (PDIP-N), 300-mil width, with standard pin 1 marking and 0.1-inch lead pitch. Pinout follows TI's documented top-view layout for N-package variants.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control: high enables A→B, low enables B→A (inverting logic) |
| 2–9 | A1–A8 | Input/output port A - bidirectional data lines tied to first bus |
| 10 | GND | Ground reference for logic and power return path |
| 11–18 | B1–B8 | Input/output port B - bidirectional data lines tied to second bus |
| 19 | OE | Output enable: low enables transceiver, high forces all outputs to high-Z |
| 20 | VCC | +5 V supply input - must be decoupled locally per best practice |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional bus isolation | Independent DIR and OE controls allow dynamic direction switching and full bus decoupling without external logic |
| TTL-compatible thresholds | VIL ≤ 0.8 V and VIH ≥ 2 V ensure interoperability with 74LS, 74ALS, and legacy microprocessor buses |
| Guaranteed 3-state leakage | IOFF ≤ ±0.1 mA at VI = 0.4 V or 2.7 V - prevents bus contention during disable |
| Low propagation skew | ΔtPLH/tPHL ≤ 1 ns across all eight channels - maintains data integrity in parallel transfers |
| Robust ESD tolerance | Class II HBM rating per JEDEC JESD22-A114 - withstands ≥2 kV human-body-model discharge |
Applications
| Industrial PLC Backplane Interface | Legacy Microprocessor Bus Extension |
|---|---|
Use Scenario: Interfacing isolated I/O modules to a central controller bus in programmable logic controllers. IC Role / Device Role / Timing Role: SN74ALS640BNSRG4 acts as a direction-controlled buffer between CPU address/data bus and field I/O expansion slots. Use Value: Enables hot-swap-capable module insertion via OE-driven isolation and DIR-synchronized data mirroring without bus lockup. | Use Scenario: Extending Z80 or 8085 CPU data bus to peripheral cards in vintage computer systems. IC Role / Device Role / Timing Role: SN74ALS640BNSRG4 serves as a bidirectional data highway between CPU and memory-mapped peripherals. Use Value: Delivers sub-12 ns propagation delay and 12 mA drive strength - meets strict timing budgets of 4–6 MHz CPU buses. |
| Test Equipment Signal Routing | Automated Test Fixture Control |
Use Scenario: Routing stimulus/response signals between DUT interface and pattern generator/analyzer in ATE systems. IC Role / Device Role / Timing Role: SN74ALS640BNSRG4 functions as a reconfigurable signal path selector under FPGA control. Use Value: High-Z isolation (≤0.1 mA leakage) prevents signal corruption during test mode switching and channel multiplexing. | Use Scenario: Controlling multiple sensor acquisition channels in factory-floor test fixtures with shared bus architecture. IC Role / Device Role / Timing Role: SN74ALS640BNSRG4 provides isolated bidirectional communication between MCU and sensor daughterboards. Use Value: Inverting logic simplifies control-state decoding in firmware; 0°C to 70°C rating matches industrial ambient requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS640BN | Same die, identical electrical specs, same PDIP-20 package - differs only in part marking and RoHS compliance status (G4 suffix denotes green/RoHS-compliant variant) | No functional difference; both rated for 0°C to 70°C and support identical load conditions | Select SN74ALS640BNSRG4 when RoHS compliance and traceable green material sourcing are required. |
| SN74AS640N | Higher-speed AS-family variant: tPLH/tPHL ≤ 7 ns, IOL = 48 mA, but higher ICC (78 mA vs. 55 mA) and tighter VIH/VIL thresholds (VIH = 2 V, VIL = 0.8 V) | Better suited for high-speed backplanes (>10 MHz), but requires stricter input noise margin and increased power budget | Choose SN74AS640N only if timing budget demands <8 ns propagation or drive >24 mA per line. |
Compared with SN74ALS640BN, SN74ALS640BNSRG4 offers identical performance with certified RoHS compliance; versus SN74AS640N, it trades speed and drive strength for lower power and relaxed input noise immunity - making it optimal for cost-sensitive, moderate-speed industrial interfaces.
Availability
SN74ALS640BNSRG4 is available at Aetrix Electronics and suitable for industrial PLC backplane interfaces, legacy microprocessor bus extensions, and automated test fixture control requiring stable component supply over extended production lifecycles.
Supply support for SN74ALS640BNSRG4 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 over 50 years of industrial-grade product heritage.
SN74ALS640BNSRG4 belongs to the 74ALS family of advanced low-power Schottky logic devices, engineered for reliable TTL-compatible bus interfacing in industrial, test, and computing equipment where speed, power efficiency, and long-term availability are critical.
FAQ
What is the maximum clock frequency supported by SN74ALS640BNSRG4?
SN74ALS640BNSRG4 does not operate on a clock; it is an asynchronous transceiver. Its usable data rate depends on propagation delay and system setup/hold timing. With tPLH/tPHL ≤ 11 ns and tPZH/tPLZ ≤ 24 ns, it reliably supports bus cycles down to ~40 ns period - enabling effective operation in 25 MHz synchronous bus environments with proper trace length control and termination.
Does SN74ALS640BNSRG4 support hot-swapping of bus modules?
Yes - SN74ALS640BNSRG4 supports controlled hot-swap operation via its OE input. When OE is held high, all A and B port outputs enter high-impedance state with leakage ≤ ±0.1 mA, electrically isolating both buses. This allows safe insertion/removal of peripheral modules without disrupting the main bus, provided OE is asserted before physical connection.
Is SN74ALS640BNSRG4 pin-compatible with SN74LS640N?
No - SN74ALS640BNSRG4 is not pin-compatible with SN74LS640N. While both are 20-pin octal transceivers, SN74LS640N uses non-inverting logic and different internal signal routing. Substituting them without circuit revision will invert data paths and cause functional failure. Always verify logic polarity and timing against the specific device's function table.
What is the meaning of the 'G4' suffix in SN74ALS640BNSRG4?
The 'G4' suffix in SN74ALS640BNSRG4 indicates TI's green/RoHS-compliant packaging: lead-free terminations (NiPdAu or matte tin), halogen-free molding compound, and compliance with EU Directive 2011/65/EU. It replaces older SN74ALS640BN variants with SnPb leads and confirms full environmental certification for modern industrial assembly lines.
Can SN74ALS640BNSRG4 drive a 50 Ω transmission line directly?
No - SN74ALS640BNSRG4 is not designed for direct 50 Ω line driving. Its output structure targets TTL fanout (10 LS-TTL loads), not RF impedance matching. Driving 50 Ω lines requires external series termination (e.g., 33 Ω resistor) and careful PCB layout to avoid reflections. For true 50 Ω applications, consider purpose-built line drivers like SN65LVDS1 or SN75ALS199.
SN74ALS640BNSRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Transceiver, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 15mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74ALS640BNSRG4 FAQ
1.How can I place an order for SN74ALS640BNSRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS640BNSRG4 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 SN74ALS640BNSRG4 reliable?
The price and inventory of SN74ALS640BNSRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS640BNSRG4 is usually 5 days.
3.What payment methods are accepted for SN74ALS640BNSRG4?
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4.How is shipping managed for SN74ALS640BNSRG4?
SN74ALS640BNSRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS640BNSRG4 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 SN74ALS640BNSRG4?
For technical support, including SN74ALS640BNSRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS640BNSRG4 requirements.
6.How does Aetrix verify that SN74ALS640BNSRG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS640BNSRG4 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 SN74ALS640BNSRG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS640BNSRG4?
All SN74ALS640BNSRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS640BNSRG4, 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 SN74ALS640BNSRG4 part is unused and in its original packaging.
Return procedure for SN74ALS640BNSRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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