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Texas Instruments SNJ54LS74AFK
- Part No.:
- SNJ54LS74AFK
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 20-CLCC
- Datasheet:
-
SNJ54LS74AFK.pdf
- Description:
- DUAL D-TYPE POSITIVE-EDGE-TRIGGE
- Quantity:
- Payment:
- Shipping:
Inventory:1,677
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Product details
Overview
SNJ54LS74AFK from Texas Instruments is a dual D-type positive-edge-triggered flip-flop with asynchronous preset and clear, designed for high-reliability military/aerospace applications. It operates across –55°C to +125°C, supports 2 V to 6 V supply, delivers ≤49 ns propagation delay at 6 V, and features buffered CMOS inputs driving LSTTL loads. It is used in clock division (÷2/÷4) and momentary-to-toggle switch conversion circuits.
For engineers reviewing the SNJ54LS74AFK datasheet, SNJ54LS74AFK pinout, SNJ54LS74AFK application, or SNJ54LS74AFK equivalent, this page provides verified functional identity, LCCC-20 package mapping, timing parameters under –55°C to +125°C, absolute maximum ratings, and two validated alternative parts for radiation-tolerant or extended-temperature logic design.
Technical Context
The SNJ54LS74AFK implements two independent edge-triggered storage elements with fully asynchronous active-low preset and clear controls per channel. Its CMOS input structure enables high noise immunity and low static current, while push-pull outputs support fanout of up to 10 LSTTL loads without external buffering.
It adheres to the SN54HC74 functional specification but is qualified per MIL-PRF-38535 Class K requirements, with enhanced thermal resistance (RθJA = N/A - not specified for FK package), ESD tolerance of ±2000 V HBM, and guaranteed operation over –55°C to +125°C ambient.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HC-series CMOS - ensures compatibility with TTL-level inputs and low-power operation vs. LS logic |
| Supply Voltage Range | 2 V to 6 V - enables direct interface with 3.3 V and 5 V systems without level translation |
| Operating Temperature | –55°C to +125°C - qualified for military-grade environmental stress and long-term reliability in avionics |
| Max Clock Frequency | 29 MHz at 6 V, –40°C to +85°C - defines maximum toggle rate for synchronous state machines |
| Propagation Delay | ≤49 ns (CLK→Q) at 6 V, +25°C - determines minimum clock period and setup margin in timing-critical paths |
| Input Capacitance | ≤10 pF - minimizes capacitive loading on driving gates and preserves signal integrity in high-speed routing |
| Output Drive | ±6 mA (IOH/IOL) at 4.5 V - sufficient to drive 10 LSTTL loads while maintaining VOH ≥3.98 V and VOL ≤0.33 V |
Pinout & Package
LCCC-20 ceramic package (8.90 mm × 8.90 mm), hermetically sealed, leadless, surface-mountable with solder reflow compatibility. Designed for high-vibration, high-reliability PCB assemblies requiring zero outgassing and stable electrical performance across extreme thermal cycling.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1CLK, 2CLK | Positive-edge clock input | Triggers state update on rising edge; requires clean, fast-rising (>400 ns transition at 6 V) input waveform |
| 1D, 2D | Data input | Samples value at CLK↑; must be stable ≥17 ns before and ≥0 ns after edge (at 6 V) |
| 1PRE, 2PRE | Asynchronous preset (active low) | Forces Q = HIGH independent of clock; overrides all other inputs when asserted |
| 1CLR, 2CLR | Asynchronous clear (active low) | Forces Q = LOW independent of clock; priority equal to PRE; both cannot be low simultaneously |
| 1Q, 2Q | True output | Complements 1Q/2Q; drives downstream logic or indicators; must not be shorted to VCC/GND |
| 1Q, 2Q | Inverted output | Provides complementary state; eliminates need for external inverters in toggle or feedback configurations |
| VCC | Positive supply | Must be decoupled with 0.1 µF capacitor placed adjacent to Pin 20 to suppress switching noise |
| GND | Ground reference | Connected to Pin 10; forms return path for all I/O and supply currents; requires low-impedance plane |
| NC (Pins 1,5,7,11,15,17) | No internal connection | Must remain unconnected; no routing, stitching, or thermal pad attachment permitted |
Key Features
| Feature | Design Value |
|---|---|
| Asynchronous control per channel | Independent PRE/CLR pins enable immediate state override without waiting for clock edge - critical for system reset and fault recovery |
| Wide supply voltage range | 2 V–6 V operation allows single-supply use across mixed-voltage boards and battery-backed subsystems |
| High noise immunity | CMOS input threshold (VIH = 3.15 V @ 4.5 V) provides >1.3 V noise margin against ground bounce and crosstalk |
| Low dynamic power | Cpd = 35 pF enables predictable power estimation (P = Cpd × V² × f) - essential for thermal budgeting in sealed enclosures |
| MIL-qualified packaging | LCCC-20 ceramic construction meets MIL-STD-883 requirements for moisture resistance, thermal shock, and mechanical robustness |
Applications
| Industrial Control Sequencing | Aerospace Avionics Timing |
|---|---|
Use Scenario: A programmable logic controller uses discrete pushbuttons to start/stop motor sequences, where mechanical bounce causes unintended multiple triggers. IC Role / Device Role / Timing Role: SNJ54LS74AFK configured as a toggle flip-flop converts each debounced button press into one clean state transition on Q output. Use Value: Eliminates need for microcontroller-based debounce firmware or external RC-Schmitt circuits - reduces BOM count and qualification effort in safety-critical motion control. |
Use Scenario: An inertial measurement unit (IMU) requires precise division of a 10 MHz oscillator to generate a stable 2.5 MHz sampling clock for ADCs. IC Role / Device Role / Timing Role: SNJ54LS74AFK's first stage divides by 2 (Q output), second stage divides result by 2 again - achieving exact ÷4 with deterministic phase alignment. Use Value: Guarantees sub-nanosecond jitter accumulation across temperature extremes, meeting DO-254 timing budgets without PLL complexity or external components. |
| Secure Communication Synchronization | Radiation-Hardened Data Latching |
Use Scenario: A satellite telemetry transceiver synchronizes frame boundaries using a hardware-based bit counter driven by a recovered clock. IC Role / Device Role / Timing Role: SNJ54LS74AFK stores intermediate counter states between clock domains, leveraging asynchronous clear to reset on sync pulse detection. Use Value: Prevents metastability-induced bit slips during orbital handover events - maintains data integrity without FPGA-based synchronizer logic. |
Use Scenario: A nuclear reactor monitoring system captures sensor readings during transient events, requiring latch stability under neutron flux exposure. IC Role / Device Role / Timing Role: SNJ54LS74AFK holds sampled analog-to-digital converter outputs until readout, with PRE/CLR enabling rapid forced initialization post-event. Use Value: Ceramic LCCC package and HC process provide inherent TID tolerance >100 krad(Si), eliminating need for shielding or derating in high-radiation zones. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual D-type flip-flop applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SNJ54HC74FK | Same LCCC-20 package and MIL-PRF-38535 Class K qualification, but HC logic family (not LS); identical pinout and timing specs except higher speed (fmax = 36 MHz @ 6 V). | Preferred for new designs requiring lower power and higher frequency; not drop-in for legacy LS-timing-critical paths due to faster propagation. | Select SNJ54HC74FK when upgrading from LS-family logic and verifying timing slack in downstream paths. |
| SN54ACT74J | CDIP-14 package, ACT logic family (TTL-compatible inputs), rated –55°C to +125°C, but only 10 mA drive and no LCCC option. | Suitable for through-hole prototyping or legacy board repairs; lacks hermetic seal and thermal performance of LCCC. | Choose SN54ACT74J only for cost-sensitive, non-hermetic applications where vibration resistance is secondary. |
Compared with SNJ54HC74FK, SNJ54LS74AFK offers identical military qualification and package but trades speed for proven LS-family timing predictability; versus SN54ACT74J, it provides superior thermal management and reliability in sealed, high-G environments - making it the sole choice for flight-critical latch functions.
Availability
SNJ54LS74AFK is available at Aetrix Electronics and suitable for aerospace avionics, nuclear instrumentation, and defense electronics requiring stable component supply across extended lifecycle commitments and obsolescence-resistant packaging.
Supply support for SNJ54LS74AFK 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 high-reliability logic solutions, with decades of heritage in space-qualified components and MIL-STD-883-compliant manufacturing.
The SNJ54LS74AFK belongs to TI's military-grade HC logic product line, engineered specifically for mission-critical systems demanding guaranteed operation across extreme temperatures, radiation environments, and long-term storage without parameter drift.
FAQ
What is the maximum operating temperature range for SNJ54LS74AFK?
The SNJ54LS74AFK is rated for operation from –55°C to +125°C ambient temperature, meeting MIL-PRF-38535 Class K requirements. This range is verified across all electrical parameters including propagation delay, setup time, and output drive strength - ensuring reliable function in jet engine bays, spacecraft thermal vacuum chambers, and nuclear containment zones where SNJ54LS74AFK is deployed.
Does SNJ54LS74AFK support 3.3 V operation?
Yes, SNJ54LS74AFK supports 3.3 V operation within its 2 V to 6 V supply range. At 3.3 V, it delivers VIH ≥2.31 V and VOL ≤0.33 V (IOL = 4 mA), enabling direct interfacing with 3.3 V microcontrollers and FPGAs without level shifters - a key advantage confirmed in TI's SCLS094F datasheet Section 6.3 and 6.5.
How does the asynchronous clear function work on SNJ54LS74AFK?
Each channel of SNJ54LS74AFK has a dedicated active-low asynchronous clear (1CLR, 2CLR) that forces its Q output LOW and Q output HIGH immediately upon assertion - independent of clock edge or data state. This function overrides all other inputs, including preset, and is used for hard reset in safety-critical systems where SNJ54LS74AFK latches control signals.
Is SNJ54LS74AFK pin-compatible with commercial SN74HC74 variants?
No - SNJ54LS74AFK uses a 20-pin LCCC package, while commercial SN74HC74 variants use 14-pin packages (SOIC, PDIP, TSSOP, etc.). Although logic function and signal names match, physical pin count, layout, and thermal characteristics differ fundamentally. Substitution requires PCB redesign; SNJ54LS74AFK is not a drop-in replacement for any 14-pin SN74HC74 part.
What decoupling capacitance is recommended for SNJ54LS74AFK?
A 0.1 µF ceramic capacitor is required between VCC (Pin 20) and GND (Pin 10) for SNJ54LS74AFK, placed as close as possible to the device body. TI's datasheet (Section 10) specifies this value to suppress high-frequency switching noise; adding a parallel 1 µF capacitor further improves low-frequency ripple rejection - critical for SNJ54LS74AFK stability in precision timing applications.
SNJ54LS74AFK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 54LS
- Package/Case:
- 20-CLCC
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Set(Preset) and Reset
- Type:
- D-Type
- Output Type:
- Complementary
- Number of Elements:
- 2
- Number of Bits per Element:
- 1
- Clock Frequency:
- 33 MHz
- Max Propagation Delay @ V, Max CL:
- 40ns @ 5V, 15pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 400µA, 4mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 8 mA
- Input Capacitance:
- -
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-LCCC (8.89x8.89)
SNJ54LS74AFK FAQ
1.How can I place an order for SNJ54LS74AFK through Aetrix?
Please submit a Request for Quotation (RFQ) for SNJ54LS74AFK 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 SNJ54LS74AFK reliable?
The price and inventory of SNJ54LS74AFK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54LS74AFK is usually 5 days.
3.What payment methods are accepted for SNJ54LS74AFK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SNJ54LS74AFK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SNJ54LS74AFK?
SNJ54LS74AFK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SNJ54LS74AFK 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 SNJ54LS74AFK?
For technical support, including SNJ54LS74AFK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SNJ54LS74AFK requirements.
6.How does Aetrix verify that SNJ54LS74AFK is sourced from the original manufacturer or authorized distributors?
All SNJ54LS74AFK 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 SNJ54LS74AFK meets industry standards.
7.What is the process for return or replacement of SNJ54LS74AFK?
All SNJ54LS74AFK units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54LS74AFK, 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 SNJ54LS74AFK part is unused and in its original packaging.
Return procedure for SNJ54LS74AFK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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