Texas Instruments SNJ54LS378J

Overview

SNJ54LS378J from Texas Instruments is a military-grade hex D-type flip-flop with enable, operating over –55°C to +125°C, featuring 16-pin CDIP package, TTL-compatible inputs/outputs, and propagation delay of 25 ns (max) at V_CC = 5 V. It serves as a synchronous data latch in radiation-tolerant control logic for aerospace sequencers and avionics timing circuits.

For engineers reviewing the SNJ54LS378J datasheet, SNJ54LS378J pinout, SNJ54LS378J application, or SNJ54LS378J equivalent, this device is selected for high-reliability edge-triggered storage where extended temperature range, leaded hermetic packaging, and MIL-PRF-38535 Class B compliance are mandatory.

Technical Context

The SNJ54LS378J implements six independent positive-edge-triggered D-type flip-flops, each with individual data (D) and clock (CLK) inputs plus a common asynchronous master reset (MR̅) and active-low output enable (OE̅). All outputs are three-state capable and share a single OE̅ control line.

It uses bipolar TTL circuitry with Schottky-clamped transistors to achieve guaranteed fan-out of 10 LS-TTL loads, input clamp diodes for transient protection, and DC noise margin of 0.4 V (min) under worst-case conditions. The device requires no external pull-ups or bypassing beyond standard 0.1 µF ceramic decoupling per supply pin.

Key Specifications

Pinout & Package

SNJ54LS378J is housed in a 16-pin Ceramic Dual In-line Package (CDIP-J), 0.300-inch wide body, with centerline lead spacing of 0.100 inch and full hermetic seal compliant with MIL-STD-1835.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SNJ54LS378J, SN54LS378J offers identical electrical performance but lacks formal Class B qualification evidence, while SN74LS378N trades hermeticity and temperature range for lower cost and RoHS compliance-making SNJ54LS378J the sole choice for flight-hardware deployment.

Availability

SNJ54LS378J is available at Aetrix Electronics and suitable for avionics data latching, missile guidance sequencing, and satellite command decoding requiring stable component supply across extended product lifecycles.

Supply support for SNJ54LS378J 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 aerospace, defense, and industrial markets.

The SNJ54LS378J belongs to TI's military logic family designed specifically for mission-critical systems demanding guaranteed operation across extreme temperatures, mechanical shock, and long-term storage without parameter drift.

FAQ

What is the maximum clock frequency supported by SNJ54LS378J?

The SNJ54LS378J has a maximum recommended clock frequency of 20 MHz, derived from its 25 ns maximum propagation delay (t_PLH/t_PHL) and guaranteed setup/hold timing margins. This limit ensures reliable edge-triggered operation under worst-case voltage (4.5 V) and temperature (–55°C) conditions. Exceeding 20 MHz may result in metastability or missed clock edges in SNJ54LS378J-based registers.

Does SNJ54LS378J include an asynchronous reset function?

Yes, SNJ54LS378J features a common active-low master reset (MR̅) input that asynchronously clears all six Q outputs to LOW regardless of clock or enable state. This MR̅ signal meets MIL-STD-883 requirements for fast, glitch-immune reset behavior and is internally debounced to prevent spurious triggering from EMI transients in SNJ54LS378J-equipped avionics modules.

Can SNJ54LS378J be used with modern PCB assembly processes?

Yes, SNJ54LS378J's CDIP (J) package is compatible with vapor-phase and convection reflow profiles specified for SnPb solder, though it requires manual or selective soldering due to its hermetic ceramic construction. Aetrix Electronics provides full process documentation-including soak time, peak temperature (215°C max), and cooling rate-for reliable SNJ54LS378J placement in mixed-technology boards.

How does SNJ54LS378J differ from SN74LS378 in terms of electrical specifications?

SNJ54LS378J and SN74LS378 share identical AC/DC electrical parameters including propagation delay, drive strength, and noise margins-but SNJ54LS378J extends V_CC tolerance to 4.5–5.5 V across –55°C to +125°C, whereas SN74LS378 is only specified for 4.75–5.25 V at 0°C to +70°C. This makes SNJ54LS378J suitable for SNJ54LS378J deployments where supply regulation is less stringent and ambient extremes exist.

Is there a drop-in replacement for SNJ54LS378J in surface-mount packaging?

No direct drop-in surface-mount replacement exists for SNJ54LS378J. While SN74LS378DR (SOIC-16) shares logic functionality, it lacks MIL-PRF-38535 qualification, operates only from 0°C to +70°C, and has different thermal and mechanical characteristics. For surface-mount migration, redesign with radiation-hardened alternatives like RHFLX16 or custom hybrid assemblies is required-not a simple SNJ54LS378J substitution.