Texas Instruments SNJ54F74J

Overview

SNJ54F74J from Texas Instruments is a dual positive-edge-triggered D-type flip-flop with independent preset and clear inputs, designed for synchronous logic control in military-grade digital systems. It operates across –55°C to 125°C, supports 100 MHz clock frequency, features 3 ns propagation delay (tPLH), and delivers rail-to-rail output swing under 20 mA sink current - used in radar timing sequencers, avionics data latching, and hardened control state machines.

For engineers reviewing the SNJ54F74J datasheet, SNJ54F74J pinout, SNJ54F74J application, or SNJ54F74J equivalent, key selection criteria include military temperature range compliance, TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V), guaranteed setup/hold times (tsu = 2 ns, th = 1 ns), and CDIP-14 hermetic packaging for high-reliability deployment.

Technical Context

This device implements two independent edge-triggered storage elements with asynchronous active-low preset and clear, enabling immediate state override regardless of clock phase. Each flip-flop samples D-input data on the rising edge of CLK only when both PRE and CLR are high, with clock triggering defined by voltage threshold rather than edge slew rate.

Logic behavior follows standard D-flip-flop truth table with non-overlapping PRE/CLR priority: low PRE forces Q = H / Q̅ = L; low CLR forces Q = L / Q̅ = H; simultaneous low PRE and CLR yields undefined (non-latched) outputs. Output drive strength is rated for 20 mA sink and –1 mA source under VCC = 4.5–5.5 V.

Key Specifications

Pinout & Package

Ceramic Dual-In-Line Package (CDIP), 14-pin, hermetically sealed, 0.300-inch width, 5.08 mm max height, lead finish: SnPb (non-RoHS).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SNJ54F74J, SNJ54LS74J trades speed for noise margin and power efficiency, while SNJ54ACT74J offers CMOS advantages but demands careful interface design - SNJ54F74J remains optimal for drop-in replacement in existing 74F-based military systems requiring proven reliability and identical pinout.

Availability

SNJ54F74J is available at Aetrix Electronics and suitable for aerospace sequencing, radar pulse control, secure communication sync, and hardened test equipment requiring stable component supply across extended temperature ranges and long lifecycle commitments.

Supply support for SNJ54F74J 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 defense, aerospace, and industrial markets.

The SNJ54F74J belongs to TI's military-grade 54F logic family, engineered for high-speed, radiation-tolerant digital control in mission-critical systems where parameter stability and long-term availability are mandatory.

FAQ

What is the maximum operating frequency of the SNJ54F74J?

The SNJ54F74J supports a maximum clock frequency of 100 MHz under recommended operating conditions (VCC = 5 V, TA = 25°C). This rating is validated across the full military temperature range (–55°C to 125°C), with timing parameters derated per datasheet curves to ensure functional reliability at temperature extremes. The SNJ54F74J achieves this performance using bipolar FET technology optimized for speed and noise immunity in critical systems.

Does the SNJ54F74J require external pull-up resistors on PRE and CLR inputs?

No, the SNJ54F74J does not require external pull-up resistors on PRE or CLR inputs. These inputs have internally biased TTL-compatible thresholds and specified IIL values (–1.8 mA at VI = 0.5 V), allowing direct connection to logic-high or microcontroller GPIOs. However, in floating-input scenarios, TI recommends tying unused PRE/CLR lines to VCC via 1–10 kΩ resistors to prevent metastability - a practice confirmed in SNJ54F74J application notes for MIL-STD-883-compliant designs.

Is the SNJ54F74J RoHS compliant?

No, the SNJ54F74J is not RoHS compliant. Its lead finish is SnPb (tin-lead), as specified in TI's packaging documentation and verified in the CDIP (J) package option addendum. This non-RoHS construction is intentional for military and aerospace applications requiring proven solder joint reliability, thermal fatigue resistance, and long-term parameter stability - characteristics validated under MIL-PRF-38535 screening protocols.

Can the SNJ54F74J be used in place of the SN74F74N in commercial designs?

The SNJ54F74J is not a direct substitute for the SN74F74N in commercial designs due to its extended temperature range (–55°C to 125°C vs. 0°C to 70°C), higher ICC (16 mA vs. 10.5 mA), and non-RoHS SnPb finish. While functionally identical and pin-compatible, SNJ54F74J's military qualification adds cost and thermal overhead unnecessary for commercial use. For commercial applications, SN74F74DR (RoHS, SOIC) or SN74F74N (PDIP, RoHS) are preferred alternatives.

What is the meaning of "nonstable" output condition when both PRE and CLR are low on the SNJ54F74J?

When both PRE and CLR are simultaneously low on the SNJ54F74J, the outputs enter a "nonstable" state (Q = Q̅ = H) that violates normal D-flip-flop logic and is not guaranteed to meet VOH specifications. This condition is transient and collapses to a valid state (Q = H or Q = L) once either PRE or CLR returns high. TI explicitly warns against relying on this state in design - it must be avoided via proper control logic sequencing or hardware interlocks to prevent undefined behavior in safety-critical systems using SNJ54F74J.