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Texas Instruments SNJ54LS640FK
- Part No.:
- SNJ54LS640FK
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SNJ54LS640FK.pdf
- Description:
- 54LS640 OCTAL BUS TRANSCEIVERS
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Inventory:2,032
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Product details
Overview
SNJ54LS640FK from Texas Instruments is a military-grade octal bus transceiver with 3-state outputs, designed for bidirectional data flow control in TTL-compatible 8-bit parallel buses. It features dual active-low output-enable inputs (OE1̅, OE2̅), independent direction control (DIR), and operates across –55°C to +125°C. Used in avionics backplanes and radiation-tolerant industrial controllers where high-reliability level-shifting and bus isolation are required.
For engineers reviewing the SNJ54LS640FK datasheet, SNJ54LS640FK pinout, SNJ54LS640FK application, or SNJ54LS640FK equivalent, key selection criteria include its LCCC-20 ceramic package, dual enable logic, DIR-controlled bidirectional operation, guaranteed military temperature range, and compatibility with legacy LS-TTL bus architectures.
Technical Context
The SNJ54LS640FK implements an 8-bit non-inverting transceiver architecture with separate control paths for direction (DIR) and output enable (OE1̅, OE2̅). Its dual OE inputs allow independent gating of A-to-B and B-to-A data paths, enabling flexible bus arbitration in multiprocessor systems.
All eight data channels share identical DC electrical characteristics: typical propagation delay of 15 ns (A→B), 17 ns (B→A); output drive capability of –15 mA sink / 0.4 mA source at VCC = 5 V; and input thresholds aligned to standard LS-TTL levels (VIL ≤ 0.8 V, VIH ≥ 2.0 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Octal non-inverting 3-state bus transceiver with direction control |
| Supply Voltage | 4.5 V to 5.5 V - ensures robust operation under noisy military power rails |
| Operating Temperature | –55°C to +125°C - qualified for extended-range military and aerospace environments |
| Propagation Delay | 15 ns (A→B), 17 ns (B→A) - enables reliable timing in 20-MHz synchronous bus systems |
| Output Drive | –15 mA sink / +0.4 mA source - sufficient to drive 10 LS-TTL loads per output |
| Package | LCCC-20 (FK), hermetically sealed ceramic, leadless - provides superior thermal stability and moisture resistance |
| Logic Family | LS-TTL compatible - interoperable with SN54/74LS series without level translation |
Pinout & Package
LCCC-20 (FK) package: 8.89 mm × 8.89 mm ceramic chip carrier with 20 I/O pads arranged in a 5×4 grid (no leads); 1.27 mm pitch; 2.03 mm max height; hermetic seal; suitable for high-reliability solder-reflow or epoxy-bond assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1–A8 | Input/Output port A | 8-bit bidirectional data bus side A - connects to local processor or controller bus |
| B1–B8 | Input/Output port B | 8-bit bidirectional data bus side B - interfaces to memory, peripheral, or backplane bus |
| DIR | Direction control input | High = A→B transfer; Low = B→A transfer - determines data flow direction |
| OE1̅ | Active-low output enable 1 | Low enables A→B path; High disables A→B outputs to high-impedance state |
| OE2̅ | Active-low output enable 2 | Low enables B→A path; High disables B→A outputs to high-impedance state |
| VCC | Positive supply | 5 V nominal power connection - must be decoupled locally with 0.1 µF ceramic capacitor |
| GND | Ground reference | Signal and power ground - requires low-inductance connection to system ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent output enables | OE1̅ and OE2̅ allow selective activation of A→B and B→A paths - enables time-multiplexed bus sharing |
| Military temperature qualification | –55°C to +125°C operation verified per MIL-PRF-38535 - supports deployment in jet engine controllers and satellite subsystems |
| LCCC hermetic packaging | FK package eliminates moisture ingress and thermal cycling fatigue - extends field life in harsh environmental deployments |
| LS-TTL compatible thresholds | VIL ≤ 0.8 V, VIH ≥ 2.0 V - ensures interoperability with legacy 74LS logic without interface circuitry |
| Matched propagation delays | 15 ns (A→B) and 17 ns (B→A) - minimizes skew in full-duplex bus configurations |
Applications
| Avionics Data Bus Interface | Industrial PLC Backplane |
|---|---|
Use Scenario: Interfacing a flight management computer's local bus to a shared ARINC 429-compatible data backbone. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing controlled data flow between dissimilar subsystems while maintaining signal integrity across long traces. Use Value: Dual OE inputs permit deterministic arbitration; military temp range ensures reliability during rapid cabin pressure and temperature changes. | Use Scenario: Isolating CPU and I/O module buses in a modular programmable logic controller rack. IC Role / Device Role / Timing Role: Octal transceiver enabling hot-swap-safe communication between processor and expansion slots via controlled 3-state gating. Use Value: DIR-controlled directionality and independent OE pins allow safe read/write sequencing during module insertion/removal. |
| Military Vehicle Control System | Satellite Onboard Computer |
Use Scenario: Connecting a radiation-hardened microcontroller to sensor acquisition and actuator driver buses in armored vehicle electronics. IC Role / Device Role / Timing Role: Level-shifting and bus-isolation transceiver ensuring noise-immune communication in high-EMI engine compartments. Use Value: LS-TTL compatibility avoids external level shifters; LCCC package withstands mechanical shock and thermal shock per MIL-STD-810. | Use Scenario: Managing data exchange between command processor and telemetry subsystem in low-earth-orbit satellite payloads. IC Role / Device Role / Timing Role: Radiation-tolerant bus buffer providing controlled, low-skew data transfer between isolated functional domains. Use Value: Hermetic LCCC construction prevents outgassing in vacuum; –55°C to +125°C rating accommodates orbital thermal cycling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SNJ54LS645FK | Same pinout and function but includes separate A/B-side output enables (OEA, OEB) instead of OE1̅/OE2̅; identical timing and temp range | Enables finer-grained per-port control in systems requiring asymmetric bus loading or staggered enable sequencing | Select SNJ54LS645FK when independent A-side and B-side output gating is required beyond directional control |
| SN54LS245J | 8-bit non-inverting transceiver with single DIR and single OE̅; CDIP-20 package; same military temp range but no dual-OE architecture | Lacks independent A→B/B→A gating - suitable only for simple unidirectional or fully synchronized bidirectional use cases | Choose SN54LS245J for cost-sensitive, space-constrained designs where dual-OE functionality is unnecessary |
Compared with SNJ54LS640FK, SNJ54LS645FK adds per-port output enable granularity without changing timing or thermal specs, while SN54LS245J reduces control flexibility to achieve lower unit cost and broader distributor availability - trade-offs center on bus arbitration complexity versus procurement simplicity.
Availability
SNJ54LS640FK is available at Aetrix Electronics and suitable for avionics data bus interfaces, industrial PLC backplanes, military vehicle control systems, and satellite onboard computers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SNJ54LS640FK 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 founded in 1930, specializing in analog, embedded processing, and high-reliability logic solutions for industrial, automotive, aerospace, and defense markets.
The SN54LS family was developed for military and aerospace applications requiring guaranteed performance across extreme temperatures and long-term reliability - SNJ54LS640FK exemplifies TI's commitment to legacy-compatible, high-integrity bus interface components.
FAQ
What is the maximum clock frequency supported by SNJ54LS640FK?
The SNJ54LS640FK is not a clocked device and has no internal clock - it is a combinatorial bus transceiver. Its usable data rate depends on system-level timing margins. With typical propagation delays of 15–17 ns and setup/hold times under 10 ns, SNJ54LS640FK supports reliable operation in synchronous bus systems up to approximately 20 MHz when paired with matched trace lengths and proper termination.
Does SNJ54LS640FK require external pull-up resistors on its 3-state outputs?
No, SNJ54LS640FK does not require external pull-up resistors on its 3-state outputs. Its outputs are designed for direct connection to LS-TTL inputs and exhibit defined high-impedance states with leakage currents below ±5 µA. Pull-ups are only needed if interfacing with CMOS loads or open-drain buses - not for standard LS-TTL bus termination.
Can SNJ54LS640FK be used in commercial-temperature applications?
Yes, SNJ54LS640FK is fully functional across 0°C to +70°C and can be used in commercial applications. However, its military-specification screening, hermetic LCCC packaging, and extended –55°C to +125°C rating make it overqualified - users should evaluate cost and availability trade-offs against commercial alternatives like SN74LS640N when military reliability is not required.
What is the meaning of "SNJ" prefix in SNJ54LS640FK?
The "SNJ" prefix identifies the part as a Texas Instruments military-grade product meeting MIL-PRF-38535 requirements. It denotes full QML certification, extended temperature qualification (–55°C to +125°C), rigorous screening (including burn-in and lot acceptance testing), and traceable manufacturing - distinguishing it from commercial "SN74" or standard military "SN54" variants.
How does the DIR pin function in SNJ54LS640FK?
The DIR pin in SNJ54LS640FK controls data flow direction: when DIR = HIGH, data passes from port A to port B (A→B); when DIR = LOW, data passes from port B to port A (B→A). This non-inverting directional control operates independently of the OE1̅ and OE2̅ enables, allowing direction to remain stable while outputs are gated into high-impedance states.
SNJ54LS640FK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SNJ54LS640FK FAQ
1.How can I place an order for SNJ54LS640FK through Aetrix?
Please submit a Request for Quotation (RFQ) for SNJ54LS640FK 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 SNJ54LS640FK reliable?
The price and inventory of SNJ54LS640FK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54LS640FK is usually 5 days.
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SNJ54LS640FK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SNJ54LS640FK 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 SNJ54LS640FK?
For technical support, including SNJ54LS640FK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SNJ54LS640FK requirements.
6.How does Aetrix verify that SNJ54LS640FK is sourced from the original manufacturer or authorized distributors?
All SNJ54LS640FK 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 SNJ54LS640FK meets industry standards.
7.What is the process for return or replacement of SNJ54LS640FK?
All SNJ54LS640FK units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54LS640FK, 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 SNJ54LS640FK part is unused and in its original packaging.
Return procedure for SNJ54LS640FK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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