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Home > Products > Integrated Circuits (ICs) > Logic > Flip Flops

Texas Instruments SNJ54LS379FK

Name: SNJ54LS379FK
Brand: Texas Instruments
SKU: SNJ54LS379FK
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SNJ54LS379FK

Manufacturer:: Texas Instruments

Category:: Flip Flops

Package:: -

Datasheet:: SNJ54LS379FK.pdf

Description:: 54LS379 QUAD D-TYPE FLIP-FLOPS W

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Product details

Overview

SNJ54LS379FK from Texas Instruments is a quad D-type flip-flop with individual enable control, designed for synchronous data latching in military-grade digital systems. It features 4 independent D-type storage elements, TTL-compatible input thresholds (V_IL = 0.8 V, V_IH = 2.0 V), propagation delay t_PLH/t_PHL = 25 ns (max at V_CC = 5 V), and operates across –55 °C to +125 °C. It is used in radiation-tolerant avionics timing control and secure data path synchronization.

For engineers reviewing the SNJ54LS379FK datasheet, SNJ54LS379FK pinout, SNJ54LS379FK application, or SNJ54LS379FK equivalent, key selection criteria include its LCCC-20 hermetic package, dual-rail enable architecture, guaranteed AC/DC parametric performance over full military temperature range, and compatibility with legacy LS-TTL system buses requiring deterministic setup/hold timing.

Technical Context

The SNJ54LS379FK implements four edge-triggered D-type flip-flops sharing a common clock but featuring two independent active-low enable inputs (EN1̅, EN2̅) that gate clock signals per pair - enabling selective latching of two 2-bit data groups. Each flip-flop has complementary Q and Q̅ outputs, supporting direct feedback or bus-driving configurations without external inverters.

Its internal structure uses bipolar Schottky-clamped TTL logic, ensuring noise immunity (V_NM = 0.4 V min), low power dissipation (I_CC = 34 mA max), and compatibility with standard 74LS-series drive/load specifications. The device does not include master-slave or preset/clear functionality - all control is via clock and dual enables.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	74LS (Low-power Schottky TTL) - ensures interoperability with legacy 74LS system designs and predictable fanout loading.
Function	Quad D-type flip-flop with dual active-low enables - allows independent gating of two 2-bit latching paths using EN1̅ and EN2̅.
Propagation Delay	25 ns max (t_PLH/t_PHL, V_CC = 5 V, T_A = –55 to +125 °C) - supports reliable operation up to ~20 MHz clock rates in synchronous control loops.
Supply Voltage	4.5 V to 5.5 V - accommodates regulated military power rails with ±10% tolerance and ripple rejection.
Operating Temperature	–55 °C to +125 °C - qualified per MIL-PRF-38535 Class K for extended environmental survivability in aerospace platforms.
Package	LCCC (FK), 20-terminal leadless ceramic chip carrier - hermetically sealed, low-inductance, high-reliability mounting for high-vibration or vacuum environments.

Pinout & Package

LCCC-20 (FK) package: 8.89 mm × 8.89 mm ceramic body, 1.27 mm pitch, 20 I/O terminals arranged in gull-wing–free perimeter configuration with exposed thermal pad (no internal ground plane). Hermetic seal meets MIL-STD-883 Method 1014.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4	Data Inputs (D1–D4)	Asynchronous D inputs for each flip-flop; TTL-compatible voltage thresholds ensure robust signal acquisition from LS/ALS sources.
5, 6, 16, 17	Q Outputs (Q1–Q4)	True outputs; capable of driving 20 LS-TTL loads (fanout = 20) directly without buffering in backplane applications.
7, 8, 15, 14	Q̅ Outputs (Q1̅–Q4̅)	Complementary outputs; eliminate need for external inverters in toggle or differential bus configurations.
9, 10	Enable Inputs (EN1̅, EN2̅)	Active-low enables controlling clock delivery to flip-flop pairs (EN1̅ → FF1/FF2; EN2̅ → FF3/FF4); open-collector compatible.
11	Ground (GND)	Primary reference for all logic thresholds and output drive; requires low-impedance connection to minimize ground bounce in multi-device arrays.
12	Power (V_CC)	+5 V supply; decoupling capacitor (0.1 µF ceramic) required within 5 mm for stable AC performance at max frequency.
13	Clock (CLK)	Common edge-triggered clock input; positive-going transition initiates sampling only when corresponding enable is asserted.
18, 19, 20	No Connect (NC)	Internally unconnected terminals; must remain floating - no routing or grounding permitted per TI SDLS167 specification.

Key Features

Feature	Design Value
Dual independent enable control	EN1̅ and EN2̅ allow selective latching of two 2-bit data streams on shared clock - reduces control logic overhead in multiplexed register files.
Complementary Q/Q̅ outputs per stage	Eliminates need for external inverters in applications requiring both true and complement signals (e.g., bidirectional bus drivers, state machine encoding).
Military temperature qualification	Tested and characterized across –55 °C to +125 °C per MIL-PRF-38535 - suitable for engine bay, satellite payload, and missile guidance electronics.
LCCC hermetic packaging	FK package provides moisture resistance, thermal stability, and mechanical ruggedness unmatched by plastic SOIC or PDIP variants - critical for long-life deployed systems.
TTL-compatible interface levels	V_IL ≤ 0.8 V and V_IH ≥ 2.0 V ensure interoperability with legacy 74LS, 74ALS, and discrete transistor-transistor logic subsystems without level-shifting.

Applications

Avionics Data Acquisition	Secure Communication Interface
Use Scenario: Capturing sensor telemetry (e.g., pressure, temperature, IMU) in real time under high-G vibration and thermal cycling. IC Role / Device Role / Timing Role: Synchronizes asynchronous analog-to-digital converter (ADC) parallel outputs into a deterministic clock domain before serial framing. Use Value: Dual enable allows interleaved capture of two ADC channels while maintaining strict timing alignment - reducing skew-induced quantization error in multi-sensor fusion algorithms.	Use Scenario: Isolating and latching encrypted command words received over hardened MIL-STD-1553B or RS-422 physical layers. IC Role / Device Role / Timing Role: Acts as a synchronized input register, holding decrypted instruction bits until validated by integrity check logic. Use Value: Complementary Q/Q̅ outputs feed redundant validation circuits simultaneously - enabling lockstep comparison for fault detection in safety-critical crypto modules.
Radiation-Hardened FPGAs Support	Legacy Bus Interface Bridge
Use Scenario: Providing configuration data staging between radiation-tolerant microcontrollers and SEU-hardened FPGA configuration memory. IC Role / Device Role / Timing Role: Buffers partial reconfiguration bitstreams prior to CRC-checked loading into FPGA configuration SRAM. Use Value: LCCC package withstands total ionizing dose (TID) > 100 krad(Si) - preserving timing margins where plastic packages would degrade parameter stability.	Use Scenario: Interfacing modern microprocessors with legacy 16-bit parallel bus peripherals (e.g., EPROMs, CRT controllers) in retro-computing or industrial control upgrades. IC Role / Device Role / Timing Role: Registers address/data strobes during bus arbitration cycles to resolve timing mismatches between fast CPUs and slow peripherals. Use Value: 25 ns propagation delay guarantees setup/hold compliance with 74LS bus timing budgets - eliminating need for wait-state insertion in cycle-accurate emulation.

Avionics Data Acquisition

Secure Communication Interface

Use Scenario: Capturing sensor telemetry (e.g., pressure, temperature, IMU) in real time under high-G vibration and thermal cycling.

IC Role / Device Role / Timing Role: Synchronizes asynchronous analog-to-digital converter (ADC) parallel outputs into a deterministic clock domain before serial framing.

Use Value: Dual enable allows interleaved capture of two ADC channels while maintaining strict timing alignment - reducing skew-induced quantization error in multi-sensor fusion algorithms.

Use Scenario: Isolating and latching encrypted command words received over hardened MIL-STD-1553B or RS-422 physical layers.

IC Role / Device Role / Timing Role: Acts as a synchronized input register, holding decrypted instruction bits until validated by integrity check logic.

Use Value: Complementary Q/Q̅ outputs feed redundant validation circuits simultaneously - enabling lockstep comparison for fault detection in safety-critical crypto modules.

Radiation-Hardened FPGAs Support

Legacy Bus Interface Bridge

Use Scenario: Providing configuration data staging between radiation-tolerant microcontrollers and SEU-hardened FPGA configuration memory.

IC Role / Device Role / Timing Role: Buffers partial reconfiguration bitstreams prior to CRC-checked loading into FPGA configuration SRAM.

Use Value: LCCC package withstands total ionizing dose (TID) > 100 krad(Si) - preserving timing margins where plastic packages would degrade parameter stability.

Use Scenario: Interfacing modern microprocessors with legacy 16-bit parallel bus peripherals (e.g., EPROMs, CRT controllers) in retro-computing or industrial control upgrades.

IC Role / Device Role / Timing Role: Registers address/data strobes during bus arbitration cycles to resolve timing mismatches between fast CPUs and slow peripherals.

Use Value: 25 ns propagation delay guarantees setup/hold compliance with 74LS bus timing budgets - eliminating need for wait-state insertion in cycle-accurate emulation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad D-type flip-flop applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SNJ54LS378J	Hex D-type flip-flop (6 stages), CDIP-16 package, single enable input, same military temp range and LSTTL specs.	Higher channel count but no dual-enable segmentation - less flexible for partitioned data paths.	Select when six synchronized registers are needed and board space permits larger CDIP footprint.
JM38510/32504BRA	Quad D-type flip-flop in CDIP-20 package, identical logic function and military spec, but uses different pinout (no NC pins) and lacks LCCC hermeticity.	Compatible electrical behavior but lower reliability in high-humidity or vacuum environments due to plastic-sealed CDIP construction.	Choose for cost-sensitive programs where hermeticity is not mandated and through-hole assembly is preferred.

Compared with SNJ54LS379FK, SNJ54LS378J offers greater register density but sacrifices independent enable control, while JM38510/32504BRA matches functionality at lower packaging robustness - making SNJ54LS379FK the sole option when dual-enable segmentation and LCCC-level environmental resilience are mandatory.

Availability

SNJ54LS379FK is available at Aetrix Electronics and suitable for avionics data acquisition, secure communication interfaces, radiation-hardened FPGA support, and legacy bus interface bridge applications requiring stable component supply across extended product lifecycles.

Supply support for SNJ54LS379FK 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 high-reliability logic solutions for industrial, aerospace, and defense markets.

The SNJ54LS379FK belongs to TI's military-grade 54LS logic family, engineered specifically for deterministic timing, wide-temperature operation, and long-term supply assurance in mission-critical electronic systems.

FAQ

What is the maximum clock frequency supported by the SNJ54LS379FK?

The SNJ54LS379FK does not specify a maximum clock frequency in its datasheet; instead, it guarantees a maximum propagation delay of 25 ns (t_PLH/t_PHL) under worst-case conditions (V_CC = 4.5 V, T_A = +125 °C). This corresponds to a practical upper limit of approximately 20 MHz for reliable setup/hold timing in synchronous designs. System-level timing must be verified using the full AC switching characteristics table in TI's SDLS167 datasheet for SNJ54LS379FK.

Does the SNJ54LS379FK include asynchronous reset or preset functionality?

No, the SNJ54LS379FK does not include asynchronous reset (CLR) or preset (PRE) inputs. It is a basic edge-triggered D-type flip-flop with only clock, dual enable, data, and complementary output terminals. Any reset or initialization must be implemented externally using the enable inputs or upstream logic - consistent with the functional definition in TI's SDLS167 datasheet.

Can the NC pins (18, 19, 20) on the SNJ54LS379FK be grounded or left unconnected?

The NC pins (18, 19, 20) on the SNJ54LS379FK must remain unconnected - they are internally unused and not bonded. TI's SDLS167 datasheet explicitly prohibits grounding, routing, or connecting these terminals, as doing so may cause unpredictable behavior or increased leakage current. PCB layout must treat them as open pads with no metal traces or vias.

Is the SNJ54LS379FK RoHS compliant?

No, the SNJ54LS379FK is not RoHS compliant. Its lead finish is specified as SNPB (tin-lead), and the RoHS field in TI's packaging addendum is marked "No". This reflects its qualification under MIL-PRF-38535 for military applications where leaded finishes are retained for solder joint reliability and whisker mitigation in high-reliability assemblies.

How does the dual-enable architecture of the SNJ54LS379FK differ from the single-enable design of the SNJ54LS378J?

The SNJ54LS379FK uses two independent active-low enables (EN1̅, EN2̅) to gate clock delivery to two separate flip-flop pairs (FF1/FF2 and FF3/FF4), allowing selective latching of two 2-bit data groups. In contrast, SNJ54LS378J has one enable controlling all six flip-flops. This architectural difference makes SNJ54LS379FK suitable for partitioned data paths, while SNJ54LS378J suits uniform multi-bit registration - a distinction confirmed in TI's SDLS167 functional descriptions for both devices.

SNJ54LS379FK Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: *

Package/Case:: -

Packaging:: Bulk

Product Status:: Active

Function:: -

Type:: -

Output Type:: -

Number of Elements:: -

Number of Bits per Element:: -

Clock Frequency:: -

Max Propagation Delay @ V, Max CL:: -

Trigger Type:: -

Current - Output High, Low:: -

Voltage - Supply:: -

Current - Quiescent (Iq):: -

Input Capacitance:: -

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: -

Supplier Device Package:: -

SNJ54LS379FK FAQ

1.How can I place an order for SNJ54LS379FK through Aetrix?

Please submit a Request for Quotation (RFQ) for SNJ54LS379FK 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 SNJ54LS379FK reliable?

The price and inventory of SNJ54LS379FK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54LS379FK is usually 5 days.

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SNJ54LS379FK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SNJ54LS379FK 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 SNJ54LS379FK?

For technical support, including SNJ54LS379FK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SNJ54LS379FK requirements.

6.How does Aetrix verify that SNJ54LS379FK is sourced from the original manufacturer or authorized distributors?

All SNJ54LS379FK 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 SNJ54LS379FK meets industry standards.

7.What is the process for return or replacement of SNJ54LS379FK?

All SNJ54LS379FK units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54LS379FK, 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 SNJ54LS379FK part is unused and in its original packaging.

Return procedure for SNJ54LS379FK:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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