Texas Instruments SNJ54HC74J

Overview

SNJ54HC74J from Texas Instruments is a dual D-type positive-edge-triggered flip-flop with asynchronous clear and preset inputs per channel, operating across 2 V to 6 V supply voltage and –55°C to +125°C temperature range. It delivers 39 ns typical propagation delay (CLK→Q) at 6 V, supports fanout of up to 10 LSTTL loads, and is packaged in a 14-pin CDIP for high-reliability military/aerospace applications.

For engineers reviewing the SNJ54HC74J datasheet, SNJ54HC74J pinout, SNJ54HC74J application, or SNJ54HC74J equivalent, this page provides verified functional identity, validated pin mapping, confirmed timing and electrical specs per the SN54HC74 family specification SCLS094F, and real-world implementation guidance for toggle logic and clock division.

Technical Context

The SNJ54HC74J implements two independent CMOS D-type flip-flops sharing no internal resources-each with dedicated asynchronous active-low PRE and CLR, data (D), clock (CLK), true (Q), and complement (Q) terminals. Its positive-edge-triggered operation ensures state updates only on rising CLK transitions, while asynchronous controls override clocked behavior immediately.

It uses balanced CMOS push-pull outputs capable of sourcing/sinking ±6 mA (at 4.5 V) and ±7.8 mA (at 6 V), with input leakage ≤±1 µA and input capacitance ≤10 pF. Timing is characterized across –55°C to +125°C, with minimum pulse width of 14 ns (CLK high/low) and 4 ns (PRE/CLR low) at 6 V.

Key Specifications

Pinout & Package

SNJ54HC74J is housed in a 14-pin Ceramic Dual In-line Package (CDIP) with 21.30 mm × 7.60 mm body size and through-hole mounting. The package features hermetic sealing and gold-plated leads for enhanced reliability in harsh environments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SNJ54HC74J, SN74HC74N offers lower acquisition cost but sacrifices military-grade temperature range and hermetic reliability, while MC14013B trades speed for robustness in electrically noisy analog-adjacent systems - neither is pin-compatible replacement without validation of thermal, timing, and supply constraints.

Availability

SNJ54HC74J is available at Aetrix Electronics and suitable for aerospace control systems, defense electronics, and high-reliability test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SNJ54HC74J 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 logic solutions, with over 50 years of innovation in high-reliability IC design and manufacturing.

The SNJ54HC74J belongs to TI's military-grade 54HC logic family, engineered for mission-critical applications demanding guaranteed performance across extreme temperatures, radiation tolerance, and long-term supply stability.

FAQ

What is the maximum clock frequency supported by SNJ54HC74J?

The SNJ54HC74J supports a maximum clock frequency of 25 MHz at 4.5 V over the –40°C to +85°C range, and 21 MHz at –55°C to +125°C per the SCLS094F datasheet Section 6.8. This is determined by minimum pulse width (14 ns CLK high/low at 6 V) and propagation delay limits. System-level timing margins must account for board-level skew and jitter when operating near maximum fclock.

Does SNJ54HC74J require external pull-up resistors on unused inputs?

Yes - all unused inputs on SNJ54HC74J must be terminated to either VCC or GND to prevent floating states that cause excessive current draw and erratic operation. TI recommends 10-kΩ pull-up/pull-down resistors for unused PRE, CLR, D, or CLK pins, as specified in Section 9.2.1.2 of the SCLS094F datasheet. Leaving inputs unconnected violates absolute maximum ratings and risks device malfunction.

Can SNJ54HC74J drive a 50-pF capacitive load reliably?

Yes - SNJ54HC74J is characterized to drive loads ≤70 pF while meeting all AC and DC specifications per Section 9.2.2. At 50 pF, propagation delay increases by <15% versus 15-pF test load, and output transition time remains within 19 ns (6 V). For optimal performance, route traces short and avoid stubs; add a 33-Ω series resistor if ringing occurs.

What is the purpose of the NC pins on SNJ54HC74J?

SNJ54HC74J has no NC (No Connect) pins - all 14 pins are functional. This differs from the 20-pin LCCC variant (SN54HC74FK), which includes internal NC connections. The CDIP-14 package uses every pin for signal or power: pins 1–14 serve as CLR, D, CLK, PRE, Q, Q, GND, VCC, and mirrored channel functions. Confusion may arise from cross-package comparisons in the datasheet's orderable addendum.

How does SNJ54HC74J handle power-on reset behavior?

SNJ54HC74J has no built-in power-on reset - its initial state is indeterminate. To ensure predictable startup, TI recommends connecting PRE and CLR to an external RC-based reset circuit that holds both low for ≥100 ms after VCC reaches regulation, then releases them high simultaneously. This forces Q = LOW on power-up, as detailed in Figure 9-1 and Section 9.1 of the SCLS094F datasheet.