Texas Instruments SNJ54LS273FK

Overview

SNJ54LS273FK from Texas Instruments is a military-grade octal D-type positive-edge-triggered flip-flop with asynchronous clear, implemented in TTL logic. It features eight independent D inputs, eight Q outputs, buffered clock and direct clear inputs, 30 MHz guaranteed clock frequency, –55°C to 125°C operating range, and LCCC-20 ceramic package. It serves as a synchronous storage register in radiation-tolerant avionics timing and control systems.

For engineers reviewing the SNJ54LS273FK datasheet, SNJ54LS273FK pinout, SNJ54LS273FK application, or SNJ54LS273FK equivalent, key selection considerations include its military temperature rating, LCCC hermetic packaging, TTL-compatible input thresholds (VIH = 2 V, VIL = 0.7 V), propagation delays under 27 ns, and compatibility with legacy 5-V digital bus architectures.

Technical Context

This device implements eight independent edge-triggered D flip-flops sharing a common clock and asynchronous clear. Each stage transfers data from D to Q on the rising edge of CLK, with setup time (20 ns) and hold time (5 ns) referenced to that edge. The clear input operates asynchronously and overrides clocked operation.

Input structure uses TTL-compatible base-emitter clamping with nominal input resistances (CLK: 6 kΩ; CLEAR: 3 kΩ; others: 8 kΩ). Output stages provide 4 mA low-level drive and –400 µA high-level sink capability at VCC = 5 V, with typical VOL = 0.25 V and VOH = 2.5 V under load.

Key Specifications

Pinout & Package

LCCC-20 (FK) package: 8.89 mm × 8.89 mm ceramic leadless chip carrier with 1.27 mm pitch, 2.03 mm max height, hermetically sealed for high-reliability applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SNJ54LS273FK, JM38510/32501B2A offers identical performance with enhanced certification reporting, while SNJ54LS273J trades hermeticity for through-hole assembly flexibility - both require no logic redesign but differ in mechanical integration and qualification scope.

Availability

SNJ54LS273FK is available at Aetrix Electronics and suitable for avionics control registers, spacecraft telemetry buffers, secure crypto key registers, and radiation-tolerant test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SNJ54LS273FK 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 high-reliability logic products for industrial, automotive, aerospace, and defense markets.

The SNJ54LS273FK belongs to TI's military logic family, designed specifically for applications demanding extended temperature operation, hermetic packaging, and compliance with MIL-PRF-38535 screening standards in mission-critical systems.

FAQ

What is the maximum clock frequency specification for SNJ54LS273FK?

The SNJ54LS273FK is guaranteed to operate up to 30 MHz across its full –55°C to 125°C temperature range, with typical maximum frequency reaching 40 MHz at 25°C. This specification is verified per SDLS090 test conditions using CL = 15 pF and RL = 2 kΩ loads, making SNJ54LS273FK suitable for deterministic timing in real-time control loops and telemetry framing circuits.

Does SNJ54LS273FK support asynchronous reset functionality?

Yes, SNJ54LS273FK includes a dedicated active-low asynchronous clear (CLR) input (Pin 1) that forces all eight Q outputs low independently of the clock signal. This feature enables immediate system-wide initialization or fault recovery without waiting for a clock edge, a critical capability in safety-critical avionics and spacecraft fault management architectures where SNJ54LS273FK is commonly deployed.

What package type and dimensions does SNJ54LS273FK use?

SNJ54LS273FK uses the LCCC-20 (FK) package: an 8.89 mm × 8.89 mm ceramic leadless chip carrier with 1.27 mm pin pitch and maximum height of 2.03 mm. Its hermetic construction meets MIL-STD-883 requirements for moisture resistance and thermal stability, distinguishing SNJ54LS273FK from plastic or DIP variants in high-reliability deployment scenarios.

How does SNJ54LS273FK differ from commercial-grade SN74LS273 variants?

SNJ54LS273FK differs from SN74LS273 in three key ways: it is screened to MIL-PRF-38535 Class B standards, rated for –55°C to 125°C operation (vs 0°C to 70°C), and packaged in hermetic LCCC-20 (FK) instead of PDIP/SOIC. These differences make SNJ54LS273FK suitable for defense and space applications where SN74LS273 would not meet environmental or reliability requirements.

What are the input voltage thresholds and output drive capabilities of SNJ54LS273FK?

SNJ54LS273FK specifies VIH ≥ 2.0 V and VIL ≤ 0.7 V at VCC = 5 V, ensuring robust noise immunity in electrically noisy platforms. Its outputs deliver IOL = 4 mA (low) and IOH = –400 µA (high) under standard test conditions, enabling direct interfacing with other TTL devices and limited fan-out to CMOS inputs without level-shifting - a key design advantage confirmed in SNJ54LS273FK electrical characteristics tables.