Texas Instruments SNJ54LS240J

Overview

SNJ54LS240J from Texas Instruments is a military-grade octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in high-reliability systems. It features dual 4-bit channels, active-low output-enable (1G and 2G), 15 ns maximum propagation delay at 5 V, ±12 mA output drive, and operates across –55°C to 125°C. It is used in aerospace avionics data buses where signal integrity and thermal stability are critical.

For engineers reviewing the SNJ54LS240J datasheet, SNJ54LS240J pinout, SNJ54LS240J application, or SNJ54LS240J equivalent, key selection criteria include its CDIP-20 package, MIL-PRF-38535 compliance, 3-state bus isolation capability, input hysteresis for noise immunity, and compatibility with legacy TTL and mixed-voltage logic interfaces.

Technical Context

The SNJ54LS240J implements two independent 4-bit inverting buffer sections, each controlled by a dedicated active-low output-enable input (1G and 2G). Its PNP-input structure reduces DC loading on upstream drivers, while built-in input hysteresis provides 400 mV noise margin-critical for noisy military environments.

Each channel passes inverted A-inputs to Y-outputs when its G input is low; outputs enter high-impedance state when G is high. The device supports terminated line driving down to 133 Ω and meets absolute maximum ratings including 7 V supply voltage and –65°C to 150°C storage temperature.

Key Specifications

Pinout & Package

SNJ54LS240J is supplied in a hermetically sealed Ceramic Dual In-line Package (CDIP-20), body size 24.20 mm × 6.92 mm, rated for high-reliability military applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal inverting buffer applications.

Compared with SNJ54LS241J, SNJ54LS240J provides inverted outputs essential for address decoding; compared with SNJ54S240J, it trades speed for lower power and superior noise immunity-making it optimal for thermally constrained, EMI-heavy military platforms.

Availability

SNJ54LS240J is available at Aetrix Electronics and suitable for aerospace avionics, defense radar subsystems, and satellite onboard computers requiring stable component supply across extended lifecycle and rigorous qualification standards.

Supply support for SNJ54LS240J 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 specializing in analog, embedded processing, and high-reliability logic solutions for industrial, automotive, and defense markets.

The SNJ54LS240J belongs to TI's military logic family, engineered specifically for bus buffering and memory address driving in harsh-environment systems where signal integrity, thermal resilience, and long-term supply assurance are mandatory.

FAQ

What is the operating temperature range of the SNJ54LS240J?

The SNJ54LS240J is rated for operation from –55°C to +125°C, meeting MIL-PRF-38535 requirements for high-reliability military and aerospace applications. This range is validated through temperature cycling, burn-in, and parametric testing per Class B or S screening levels. The SNJ54LS240J maintains specified VOH, VOL, and tpd performance across this full range when operated within recommended VCC and load conditions.

Does the SNJ54LS240J support 3.3-V logic inputs?

Yes, the SNJ54LS240J accepts 3.3-V logic inputs reliably: its VIH minimum is 2.0 V and it tolerates inputs down to 2 V, making it interoperable with 3.3-V FPGAs and microcontrollers in mixed-voltage systems. No external level-shifting circuitry is required. This capability is confirmed in the "Inputs Tolerant Down to 2 V" feature and verified in Electrical Characteristics tables under Recommended Operating Conditions.

How does the SNJ54LS240J achieve noise immunity on bus lines?

The SNJ54LS240J achieves 400 mV noise immunity through built-in input hysteresis (VT+ − VT− = 0.2–0.4 V), which raises the effective input threshold for rising edges and lowers it for falling edges. This hysteresis is inherent to the LS-TTL input structure and is explicitly documented in Section 6.5 Electrical Characteristics. It prevents false triggering from EMI-induced glitches on long PCB traces or backplane connections.

What is the maximum propagation delay for the SNJ54LS240J at 5 V?

The maximum propagation delay (tpd) for the SNJ54LS240J is 15 ns at VCC = 5 V, TA = 25°C, RL = 667 Ω, and CL = 45 pF, as specified in Section 6.7 Switching Characteristics. This value applies to both tPLH and tPHL transitions and represents worst-case performance across process, voltage, and temperature corners for the LS family variant.

Is the SNJ54LS240J pin-compatible with other SNJ54LS24x variants?

Yes, the SNJ54LS240J shares identical pinout and package (CDIP-20) with SNJ54LS241J and SNJ54LS244J. All three have the same 20-pin arrangement, terminal functions, and mechanical footprint. However, functional differences exist: SNJ54LS240J provides inverting outputs, SNJ54LS241J is non-inverting, and SNJ54LS244J offers complementary (inverting + non-inverting) outputs per channel - requiring logic-level verification before substitution.