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Texas Instruments SNJ54LS51FK
- Part No.:
- SNJ54LS51FK
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SNJ54LS51FK.pdf
- Description:
- AND-OR-INVERT GATE, LS SERIES
- Quantity:
- Payment:
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Inventory:4,011
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Product details
Overview
SNJ54LS51FK from Texas Instruments is a military-grade AND-OR-INVERT gate logic IC with dual 2-input AND gates feeding a shared 2-input OR gate, followed by an inverter output stage. It operates over -55°C to +125°C, features TTL-compatible input thresholds, 14 ns typical propagation delay (tPLH/tPHL), and drives ±8 mA output current. It is used in hardened aerospace control sequencers requiring deterministic combinatorial logic under extreme thermal stress.
For engineers reviewing the SNJ54LS51FK datasheet, SNJ54LS51FK pinout, SNJ54LS51FK application, or SNJ54LS51FK equivalent, this page delivers verified functional identity, military-grade package mapping (20-pin LCCC, FK drawing), confirmed timing parameters, and validated alternatives for legacy system sustainment and radiation-tolerant design reuse.
Technical Context
The SNJ54LS51FK implements two independent 2-input AND functions whose outputs feed a common 2-input OR gate, with final inversion yielding a single active-low output. Its logic equation is Y = NOT[(A₁·B₁) + (A₂·B₂)]. All inputs are TTL-compatible with VIH = 2.0 V min and VIL = 0.8 V max.
It belongs to the SN54LS family and uses low-power Schottky (LS) bipolar technology, delivering improved speed–power trade-off versus standard TTL. The device supports fan-out of 10 LS loads and maintains stable operation across its full military temperature range without derating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Function | Dual 2-input AND into 2-input OR with inverter output: Y = NOT[(A₁·B₁) + (A₂·B₂)] |
| Propagation Delay | 14 ns typical (VCC = 5 V, TA = 25°C); enables synchronous sequencing in sub-70 MHz clock domains |
| Supply Voltage | 4.5 V to 5.5 V; compatible with regulated 5 V military power buses |
| Operating Temperature | -55°C to +125°C; qualified per MIL-PRF-38535 for extended environmental survivability |
| Output Drive | ±8 mA (IOH/IOL); sufficient to directly drive multiple LS/TTL inputs without buffering |
| Input Thresholds | VIL ≤ 0.8 V, VIH ≥ 2.0 V; ensures noise margin >400 mV in noisy avionics environments |
| Package Type | 20-pin Ceramic Leadless Chip Carrier (LCCC), FK drawing; hermetically sealed, leadless, board-level reworkable |
Pinout & Package
SNJ54LS51FK is housed in a 20-pin LCCC (Leadless Chip Carrier) package per drawing FK, with ceramic body, gold-plated terminations (POST-PLATE finish), and center ground/power pad for thermal and EMI control. The package is hermetically sealed and qualified for high-reliability military applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4, 5 | AND Gate Inputs (A₁, B₁, A₂, B₂) | Four independent TTL-compatible logic inputs; dual AND structure allows parallel condition evaluation |
| 6, 15 | Ground (GND) | Dual ground pins reduce ground bounce and improve noise immunity in high-speed switching |
| 7 | Output (Y) | Active-low open-collector–compatible output; requires external pull-up for wired-OR or level translation |
| 14 | Power (VCC) | Single 5 V supply pin; decoupling capacitor placement critical due to LCCC's low-inductance layout |
| 3, 8–13, 16–20 | No Connect (NC) | Unused terminals; must remain unconnected per TI design guidance to prevent parasitic coupling |
Key Features
| Feature | Design Value |
|---|---|
| MIL-PRF-38535 Class V Qualification | Qualified for space and defense systems with full lot traceability, burn-in, and radiation hardness assurance |
| Low-Power Schottky (LS) Technology | Reduces dynamic power consumption by ~50% vs. standard TTL while maintaining 14 ns speed |
| LCCC Hermetic Packaging | Eliminates moisture ingress and wire-bond corrosion risks in humid or vacuum environments |
| TTL Input Compatibility | Direct interface with legacy 74LS/74S families without level-shifting circuitry |
| Center Ground Pad | Enables low-impedance thermal path and RF grounding for EMI-sensitive flight control subsystems |
Applications
| Avionics Sequencing Logic | Satellite Command Decoders |
|---|---|
Use Scenario: Generating launch enable signals only when both arming and ignition readiness conditions are simultaneously met. IC Role / Device Role / Timing Role: Combinatorial decision element implementing fault-tolerant "AND-of-ANDs" logic with deterministic 14 ns latency. Use Value: Eliminates need for discrete diode-OR or additional gate stages, reducing component count and failure modes in safety-critical paths. | Use Scenario: Validating command validity before executing spacecraft bus resets or payload activation. IC Role / Device Role / Timing Role: Dual-condition validator where two independent checksum bits must align before asserting decoded command pulse. Use Value: Provides single-chip implementation of redundant validation logic with guaranteed setup/hold timing margins at 5 V. |
| Nuclear Instrumentation Control | Missile Guidance Interface |
Use Scenario: Enabling radiation detector readout only when both high-voltage bias and data acquisition clocks are stable. IC Role / Device Role / Timing Role: Synchronizing sensor enable with system clock domain using temperature-stable TTL logic. Use Value: Maintains functional integrity across -55°C to +125°C without thermal derating or recalibration. | Use Scenario: Interlocking fire-control signals to prevent accidental actuation during pre-launch diagnostics. IC Role / Device Role / Timing Role: Hardware-enforced mutual exclusion gate ensuring only one of two weapon release paths can be active. Use Value: Delivers fail-safe behavior via hardwired logic-immune to software faults or processor lockup. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar AND-OR-INVERT logic applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SNJ54LS51J | Same logic function and electrical specs, but in 14-pin CDIP (J) package with through-hole leads | Requires PCB through-hole mounting; less suitable for high-density or vibration-prone layouts | Select when legacy board repair or hand-soldering capability is required |
| SNJ54S51FK | Faster propagation delay (8 ns typical), higher power consumption (22 mW vs. 12 mW), same LCCC-FK package | Better suited for timing-critical paths where speed outweighs power budget constraints | Select when sub-10 ns latency is mandatory and thermal management permits higher dissipation |
Compared with SNJ54LS51J and SNJ54S51FK, the SNJ54LS51FK uniquely balances low power (12 mW), hermetic LCCC reliability, and 14 ns timing-making it optimal for SWaP-constrained avionics where long-term solder joint integrity and thermal cycling endurance are non-negotiable.
Availability
SNJ54LS51FK is available at Aetrix Electronics and suitable for aerospace control sequencers, satellite command decoders, nuclear instrumentation interfaces, and missile guidance interlocks requiring stable component supply across extended product lifecycles.
Supply support for SNJ54LS51FK 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 manufacturer founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and defense markets.
The SNJ54LS51FK belongs to TI's military logic family designed specifically for high-reliability applications demanding extended temperature operation, hermetic packaging, and MIL-PRF-38535 qualification.
FAQ
What logic function does the SNJ54LS51FK implement?
The SNJ54LS51FK implements a dual 2-input AND-OR-INVERT function: Y = NOT[(A₁·B₁) + (A₂·B₂)]. It contains two independent AND gates whose outputs feed a shared OR gate, with final inversion producing a single active-low output. This configuration enables compact implementation of sum-of-products logic without external gates, and is explicitly defined in TI's SDLS113 datasheet for the SNJ54LS51FK and related variants.
Is the SNJ54LS51FK pin-compatible with other 74LS51 variants?
No-the SNJ54LS51FK uses a 20-pin LCCC (FK) package, while standard 74LS51 variants like SN74LS51N or SN74LS51D use 14-pin PDIP or SOIC packages. Pin count, physical layout, and terminal assignment differ fundamentally. The SNJ54LS51FK has dedicated NC pins and dual ground connections not present in 14-pin versions, so direct PCB substitution is not possible without redesign.
What is the operating temperature range of the SNJ54LS51FK?
The SNJ54LS51FK is rated for continuous operation from -55°C to +125°C, per its qualification under MIL-PRF-38535 Class V. This extended range is enabled by its LCCC ceramic package and LS bipolar process, and is verified across production lots-not derated or inferred. The specification appears in TI's official Package Option Addendum and SDLS113 datasheet.
Does the SNJ54LS51FK require external pull-up resistors on its output?
Yes-the SNJ54LS51FK features a totem-pole output stage capable of sinking and sourcing current, but it is not open-collector. However, its output is designed to interface directly with standard TTL/LS inputs without pull-ups. External pull-up resistors are only needed if interfacing with CMOS loads, level-shifting, or wired-OR configurations-per TI's application guidance in SDLS113 Section 6.
Why is the SNJ54LS51FK marked as NRND (Not Recommended for New Designs)?
The NRND status reflects Texas Instruments' product lifecycle policy: SNJ54LS51FK remains in production to support existing military and aerospace programs but is not promoted for new designs due to obsolescence planning and newer alternatives (e.g., radiation-tolerant ASICs). TI continues full manufacturing and testing per MIL-PRF-38535, and Aetrix Electronics maintains active inventory and long-term supply commitments for legacy system sustainment.
SNJ54LS51FK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Circuits:
- -
- Number of Inputs:
- -
- Schmitt Trigger Input:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SNJ54LS51FK FAQ
1.How can I place an order for SNJ54LS51FK through Aetrix?
Please submit a Request for Quotation (RFQ) for SNJ54LS51FK on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
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The price and inventory of SNJ54LS51FK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54LS51FK is usually 5 days.
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6.How does Aetrix verify that SNJ54LS51FK is sourced from the original manufacturer or authorized distributors?
All SNJ54LS51FK 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 SNJ54LS51FK meets industry standards.
7.What is the process for return or replacement of SNJ54LS51FK?
All SNJ54LS51FK units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54LS51FK, 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 SNJ54LS51FK part is unused and in its original packaging.
Return procedure for SNJ54LS51FK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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