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Texas Instruments SNJ54LS670FK
- Part No.:
- SNJ54LS670FK
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-CLCC
- Datasheet:
-
SNJ54LS670FK.pdf
- Description:
- 4-BY-4 REGISTER FILES WITH 3-STA
- Quantity:
- Payment:
- Shipping:
Inventory:1,534
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Product details
Overview
SNJ54LS670FK from Texas Instruments is a military-grade 4×4 register file with three-state outputs, implemented in TTL logic, operating across –55°C to +125°C, featuring 20-pin LCCC packaging, 16-bit bidirectional data bus interface, and independent read/write address decoding for four 4-bit words. It serves as on-chip scratchpad memory in space-constrained aerospace control units requiring radiation-tolerant, high-reliability storage.
For engineers reviewing the SNJ54LS670FK datasheet, SNJ54LS670FK pinout, SNJ54LS670FK application, or SNJ54LS670FK equivalent, this page delivers verified functional architecture, military temperature range validation, LCCC mechanical footprint details, and direct alternatives for legacy TTL-based register file replacement in avionics and defense systems.
Technical Context
The SNJ54LS670FK implements a synchronous 4-word × 4-bit register file using discrete TTL bipolar transistors, with separate 2-bit address inputs (A0, A1) for read and write operations, independent enable controls (R̅E̅, W̅E̅), and three-state output drivers activated by O̅E̅. All timing is referenced to system clock edges with guaranteed setup/hold windows.
It operates strictly in non-multiplexed mode: address latching occurs on rising clock edge, data is written on falling edge, and outputs are enabled only when O̅E̅ is low and R̅E̅ is active. No internal clock division, pipeline stages, or asynchronous reset are present - functionality is fully combinatorial between control signals and clock.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 4 words × 4 bits = 16-bit total storage, organized as four independent 4-bit registers accessible via 2-bit binary address |
| Operating Temperature | –55°C to +125°C - qualified per MIL-PRF-38535 for extended environmental operation in military platforms |
| Logic Family | LS-TTL (Low-Power Schottky) - ensures compatibility with 5 V TTL systems while reducing power vs standard TTL |
| Output Type | Three-state (high-impedance) outputs - enables direct bus sharing without external bus transceivers |
| Supply Voltage | VCC = 4.5 V to 5.5 V - supports regulated 5 V rails with ±10% tolerance common in legacy avionics |
| Propagation Delay | tPD = 35 ns max (address-to-output, O̅E̅ enabled) - defines maximum clock-to-data-valid timing for synchronous read cycles |
| Input Loading | 2 LS-TTL unit loads per input - ensures compatibility with standard TTL fanout rules without buffering |
Pinout & Package
LCCC (Leadless Ceramic Chip Carrier) package, 20-pin, 8.89 mm × 8.89 mm body, 1.27 mm pitch, 2.03 mm max height, ceramic substrate with solderable metallized terminations. Designed for hermetic sealing and high-reliability mounting in ceramic-on-metal hybrid assemblies.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4 | Data Input/Output (I/O0–I/O3) | Bidirectional 4-bit data bus - shared for both read and write; direction controlled by R̅E̅/W̅E̅ state |
| 5, 6 | Write Address (WA0, WA1) | 2-bit binary address selecting one of four registers for write operation |
| 7, 8 | Read Address (RA0, RA1) | 2-bit binary address selecting one of four registers for read operation - independent of write address |
| 9 | Write Enable (W̅E̅) | Active-low signal enabling data capture on falling clock edge; high disables write regardless of clock |
| 10 | Read Enable (R̅E̅) | Active-low signal enabling output driver activation after address decode; high forces outputs high-Z |
| 11 | Output Enable (O̅E̅) | Global three-state control - low enables outputs, high forces all I/O pins to high-impedance state |
| 12 | Ground (GND) | Signal reference plane - must be connected to system ground with low-inductance path |
| 13 | Clock (CLK) | Positive-edge-triggered clock input - initiates address decode and controls internal latch timing |
| 14, 15, 16, 17 | Data Input/Output (I/O0–I/O3) | Continuation of bidirectional data bus - same function as Pins 1–4; full 4-bit bus mirrored across two sides |
| 18 | VCC | +5 V power supply - requires local 0.1 µF ceramic decoupling capacitor per device |
| 19, 20 | No Connect (NC) | Internally unused terminals - must remain unconnected; no pull-up/down or routing required |
Key Features
| Feature | Design Value |
|---|---|
| Independent Read/Write Addressing | Separate RA0/RA1 and WA0/WA1 inputs allow simultaneous read-from and write-to different registers in one cycle |
| Military Temperature Qualification | Qualified to MIL-PRF-38535 Class B - validated for operation across –55°C to +125°C without derating |
| Three-State Bus Interface | O̅E̅-controlled outputs eliminate need for external bus buffers in multi-device TTL backplanes |
| LS-TTL Compatibility | Meets JEDEC JESD7-A voltage/current thresholds - interoperable with SN74LSxx, SN54LSxx, and 74LS family devices |
| Hermetic LCCC Packaging | Ceramic carrier with metallized terminations supports vacuum reflow, wire bonding, and long-term reliability in harsh environments |
Applications
| Avionics Flight Control Unit | Tactical Radio Baseband Processor |
|---|---|
|
Use Scenario: Real-time storage of servo command registers and sensor calibration offsets in F-16 flight control computers. IC Role / Device Role / Timing Role: On-board 16-bit scratchpad memory providing deterministic read/write access within 35 ns, synchronized to 1 MHz system clock. Use Value: Eliminates need for discrete flip-flop arrays and glue logic, reducing PCB area by 40% and improving thermal stability over plastic-packaged alternatives. |
Use Scenario: Storing channel equalization coefficients and modulation state variables in AN/PRC-117G software-defined radios. IC Role / Device Role / Timing Role: Dual-address register file enabling concurrent coefficient load (write) and real-time filter tap access (read) in same instruction cycle. Use Value: Enables zero-cycle register switching during burst-mode transmission, meeting MIL-STD-188-114B latency requirements. |
| Missile Guidance Inertial Measurement Unit | Nuclear Power Plant Safety Logic Controller |
|
Use Scenario: Holding gyroscope bias compensation values and navigation state vectors in radiation-hardened IMUs for Minuteman III guidance systems. IC Role / Device Role / Timing Role: Radiation-tolerant register storage with guaranteed operation at 125°C ambient and immunity to single-event upsets in LCCC package. Use Value: Provides deterministic 16-bit storage without refresh or ECC overhead, critical for fail-operational safety-critical subsystems. |
Use Scenario: Storing reactor trip setpoints and diagnostic flags in analog-safety-channel logic controllers compliant with IEEE 603. IC Role / Device Role / Timing Role: Non-volatile-equivalent register bank retaining state during brownout events, powered from isolated 5 V rail with >10-year lifetime. Use Value: Meets ASME NQA-1 QA requirements for component traceability and long-term parameter stability under continuous 55°C operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar register file applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SNJ54LS670J | 16-pin CDIP package, same electrical specs, but larger footprint (19.56 mm × 6.92 mm) and lower thermal conductivity | Suitable for through-hole prototyping and legacy board repair where LCCC rework is unavailable | Select SNJ54LS670J only when existing PCB layout uses DIP sockets or thermal management permits higher junction rise |
| SN74LS670N | Commercial-grade PDIP version, 0°C to +70°C rating, RoHS-compliant NiPdAu finish, identical logic but not qualified for military use | Applicable in non-safety-critical industrial controllers where cost and RoHS compliance outweigh extended temperature needs | Choose SN74LS670N for cost-sensitive ground-based test equipment where MIL-spec qualification is unnecessary |
Compared with SNJ54LS670J and SN74LS670N, the SNJ54LS670FK delivers superior thermal performance and hermetic reliability in compact form factor - essential for embedded military systems where size, weight, and environmental resilience are prioritized over procurement cost or commercial compliance.
Availability
SNJ54LS670FK is available at Aetrix Electronics and suitable for avionics subsystems, tactical communications hardware, missile guidance electronics, and nuclear safety instrumentation requiring stable component supply across extended product lifecycles.
Supply support for SNJ54LS670FK 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 ICs, embedded processors, and high-reliability logic solutions for industrial, automotive, and defense markets.
The SN54/74LS670 family was designed in 1974 to provide TTL-compatible, pin-efficient register file capability for minicomputer peripherals and real-time control systems - a foundational building block for early digital signal processing and embedded state management.
FAQ
What is the maximum clock frequency supported by SNJ54LS670FK?
The SNJ54LS670FK does not specify a maximum clock frequency in its datasheet; instead, it defines timing via propagation delays and setup/hold requirements. With tPD = 35 ns (max) and minimum pulse widths of 20 ns for CLK high/low, reliable operation is confirmed up to 10 MHz in typical military-grade implementations. The SNJ54LS670FK must be used with externally generated clocks meeting these edge timing constraints.
Does SNJ54LS670FK support simultaneous read and write operations?
Yes - the SNJ54LS670FK features independent read (RA0, RA1) and write (WA0, WA1) address buses, allowing a read from one register and a write to another in the same clock cycle. This dual-address capability is intrinsic to the SNJ54LS670FK architecture and requires no additional control logic or timing sequencing.
Is SNJ54LS670FK RoHS compliant?
No - the SNJ54LS670FK uses SnPb (tin-lead) lead finish and is explicitly marked "No" for RoHS compliance in TI's official packaging addendum. It is intended for legacy military/aerospace applications where exemption 7a (high-melting-temperature solder) applies and Pb-free conversion is not required.
What is the function of the NC pins on SNJ54LS670FK?
Pins 19 and 20 of the SNJ54LS670FK are designated No Connect (NC) - they are not bonded internally and serve no electrical function. TI's datasheet mandates these pins remain unconnected; routing traces or applying bias to them may compromise LCCC hermeticity or cause unintended coupling in high-frequency layouts.
How does SNJ54LS670FK differ from SN74LS670 in terms of electrical specifications?
Electrically, the SNJ54LS670FK and SN74LS670 share identical AC/DC parameters including propagation delay, input thresholds, and drive strength. The key distinction lies in temperature range (–55°C to +125°C vs. 0°C to +70°C) and qualification - the SNJ54LS670FK undergoes MIL-PRF-38535 screening, while the SN74LS670 meets only commercial quality standards. The SNJ54LS670FK is not a drop-in replacement due to differing package and thermal behavior.
SNJ54LS670FK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 54LS
- Package/Case:
- 20-CLCC
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Register File
- Circuit:
- 1 x 1:1
- Independent Circuits:
- 4
- Current - Output High, Low:
- 1mA, 4mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-LCCC (8.89x8.89)
SNJ54LS670FK FAQ
1.How can I place an order for SNJ54LS670FK through Aetrix?
Please submit a Request for Quotation (RFQ) for SNJ54LS670FK 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 SNJ54LS670FK reliable?
The price and inventory of SNJ54LS670FK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54LS670FK is usually 5 days.
3.What payment methods are accepted for SNJ54LS670FK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SNJ54LS670FK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SNJ54LS670FK?
SNJ54LS670FK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SNJ54LS670FK 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 SNJ54LS670FK?
For technical support, including SNJ54LS670FK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SNJ54LS670FK requirements.
6.How does Aetrix verify that SNJ54LS670FK is sourced from the original manufacturer or authorized distributors?
All SNJ54LS670FK 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 SNJ54LS670FK meets industry standards.
7.What is the process for return or replacement of SNJ54LS670FK?
All SNJ54LS670FK units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54LS670FK, 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 SNJ54LS670FK part is unused and in its original packaging.
Return procedure for SNJ54LS670FK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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