Texas Instruments SNJ54LS374FK

Overview

SNJ54LS374FK from Texas Instruments is an octal D-type edge-triggered flip-flop with 3-state bus-driving outputs, designed for high-capacitance bus interfacing in military-grade systems. It features positive-edge clock triggering, output-enable (OC) control with independent high-impedance state, and operates across –55°C to 125°C. Key parameters include 5 V nominal supply, 35 MHz max clock frequency, 12 ns typical propagation delay (tPLH), and ±24 mA output drive capability.

For engineers reviewing the SNJ54LS374FK datasheet, SNJ54LS374FK pinout, SNJ54LS374FK application, or SNJ54LS374FK equivalent, this device is selected for synchronous data latching in legacy aerospace avionics, MIL-STD-1553B interface buffers, and radiation-tolerant embedded control registers where temperature resilience and bus isolation are critical.

Technical Context

The SNJ54LS374FK implements eight independent D-type flip-flops synchronized on the rising edge of CLK, with each Q output capturing the logic level present at its D input at clock transition. Its buffered OC input controls all eight outputs simultaneously, placing them in high-impedance without affecting internal latch states-enabling bidirectional bus arbitration.

This device belongs to the 54LS logic family and uses bipolar transistor-transistor logic (TTL) with Schmitt-trigger–free inputs (unlike 'S variants). It requires no external pull-ups or interface components when driving standard 50 Ω–667 Ω bus loads, and retains data during OC assertion, supporting seamless register read-modify-write cycles.

Key Specifications

Pinout & Package

LCCC (FK) package: 20-terminal, leadless ceramic chip carrier with solderable metallized pads; hermetically sealed, suitable for high-reliability military applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SNJ54LS374J and SNJ54LS374W, the SNJ54LS374FK offers superior board-level reliability via leadless LCCC construction, reduced parasitic inductance for high-frequency signal integrity, and optimized thermal performance in conduction-cooled chassis-making it the preferred choice for new high-density military designs.

Availability

SNJ54LS374FK is available at Aetrix Electronics and suitable for aerospace avionics data buffering, MIL-STD-1553B interface registers, and rad-hard embedded control registers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SNJ54LS374FK 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 specializing in analog, embedded processing, and high-reliability logic solutions for industrial, automotive, and defense markets.

The SNJ54LS374FK belongs to TI's military-grade 54LS logic family, engineered for deterministic timing, bus isolation, and operation under extreme environmental stress-targeting avionics, missile guidance, and secure communications systems.

FAQ

What is the maximum clock frequency supported by SNJ54LS374FK?

The SNJ54LS374FK supports a maximum clock frequency of 35 MHz under recommended operating conditions (VCC = 5 V, CL = 45 pF, TA = 25°C). This value is measured with all outputs loaded and reflects the device's ability to reliably capture data on the rising edge of CLK without setup/hold violations. At temperature extremes or higher capacitive loads, derating may be required per MIL-PRF-38535 test reports.

Does SNJ54LS374FK have Schmitt-trigger inputs?

No, the SNJ54LS374FK does not feature Schmitt-trigger inputs. Unlike the 'S-series variants (e.g., SNJ54S374), the 'LS374 family-including SNJ54LS374FK-uses standard TTL input thresholds (VIH = 2.0 V, VIL = 0.8 V) without hysteresis. This is confirmed in the SDLS165B datasheet, which explicitly assigns Schmitt-trigger buffering only to 'S373 and 'S374 devices.

How does the output-enable (OC) pin affect internal flip-flop operation in SNJ54LS374FK?

The OC pin in SNJ54LS374FK controls only the output drivers-not internal logic. When OC is high, all Q outputs enter high-impedance, but the flip-flops retain their stored data and continue responding to CLK edges. New data can be latched on subsequent rising CLK edges even while outputs remain disabled, enabling non-intrusive register updates during bus arbitration.

What is the supply current consumption of SNJ54LS374FK under typical operating conditions?

SNJ54LS374FK draws 27–40 mA of supply current (ICC) under recommended operating conditions, depending on output loading and state. Per SDLS165B, ICC is specified as 27 mA (min) to 40 mA (max) for 'LS374 devices at VCC = 5 V, with OC held at 4.5 V. Current increases with higher output switching activity and decreases in high-Z mode due to reduced driver conduction.

Is SNJ54LS374FK compliant with MIL-PRF-38535?

Yes, SNJ54LS374FK is manufactured and tested to MIL-PRF-38535 requirements for Class B (space-qualified) and Class S (standard military) devices. The datasheet states that "on products compliant to MIL-PRF-38535, all parameters are tested unless otherwise noted," and TI's packaging addendum confirms its status as an active production part under that specification with full screening including temperature cycling and burn-in.