Texas Instruments SN54LS673J

Overview

SN54LS673J from Texas Instruments is a 16-bit parallel-in/serial-out shift register with synchronous load, master reset, and complementary serial outputs (Q and Q̅). It operates over –55°C to +125°C, supports TTL-level inputs, and features dual-rail output capability for bidirectional data flow control in military-grade digital systems.

For engineers reviewing the SN54LS673J datasheet, SN54LS673J pinout, SN54LS673J application, or SN54LS673J equivalent, this device serves as a high-reliability serial data converter in avionics bus interfaces, secure telemetry controllers, and radiation-tolerant test instrumentation where deterministic timing and wide-temperature operation are mandatory.

Technical Context

The SN54LS673J implements a 16-stage static shift register using bipolar TTL logic, with independent clock (CLK) and load (LOAD) control enabling synchronous parallel capture followed by serial shifting. Its master reset (MR) clears all stages asynchronously, while Q and Q̅ outputs provide simultaneous true and inverted serial streams.

Designed for military applications, it uses ceramic dual-in-line packaging (CDIP-J, 24-pin) with hermetic sealing per MIL-STD-1835, supporting full DC–15 MHz shift rates at V_CC = 5 V and guaranteed operation across –55°C to +125°C without derating.

Key Specifications

Pinout & Package

Ceramic Dual-In-Line Package (CDIP-J), 24-pin, 0.600-inch body width, hermetically sealed with ceramic lid and glass frit seal per MIL-STD-1835 GDIP3-T24. Pin 1 marked by index notch or dot on cap.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit shift register applications.

Compared with SN54LS674J and SN74LS673DW, the SN54LS673J uniquely delivers military-grade PISO conversion in a hermetic ceramic package - essential for aerospace, defense, and high-reliability embedded systems where environmental robustness and deterministic timing cannot be compromised.

Availability

SN54LS673J is available at Aetrix Electronics and suitable for aerospace telemetry encoders, secure command decoders, avionics built-in test systems, and radiation-hardened data loggers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN54LS673J 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 industrial, automotive, and defense markets.

The SN54LS673J belongs to TI's military-grade TTL logic family, designed specifically for applications demanding guaranteed operation across extreme temperatures, mechanical shock, and long-term reliability in mission-critical systems.

FAQ

What is the maximum clock frequency supported by the SN54LS673J?

The SN54LS673J supports a maximum clock frequency of 15 MHz under nominal conditions (V_CC = 5 V, T_A = 25°C). At the full military temperature range (–55°C to +125°C), timing is guaranteed per datasheet AC specifications, with propagation delay remaining ≤40 ns. This makes the SN54LS673J suitable for real-time serial data conversion in high-speed telemetry and command links where cycle-accurate timing is critical.

Does the SN54LS673J support both parallel load and serial shift in the same clock cycle?

No - the SN54LS673J uses separate control signals: LOAD enables parallel capture on the next rising CLK edge, while absence of LOAD enables serial shifting on each rising CLK edge. The two modes are mutually exclusive per clock cycle. This separation prevents metastability and ensures deterministic behavior in safety-critical systems, a key design feature confirmed in the SDLS195 datasheet timing diagrams.

What is the function of the Q̅ output on the SN54LS673J?

The Q̅ output on the SN54LS673J provides the logical complement of the primary serial output Q. It is not an open-collector or tri-state signal - it is a fully buffered active-high/inverted output. This allows direct interfacing with differential line drivers or eliminates the need for external inverters in feedback configurations, reducing component count in avionics and defense subsystems where board space and reliability are constrained.

Is the SN54LS673J pin-compatible with the SN74LS673DW?

No - although both share identical logic functionality and 24-pin count, the SN54LS673J uses a ceramic dual-in-line package (CDIP-J) with 0.600-inch width and through-hole mounting, while the SN74LS673DW uses a plastic SOIC-24 package with 0.300-inch width and gull-wing leads. Their pinouts differ in physical layout and thermal/mechanical specifications; PCB redesign is required for substitution.

How is master reset (MR) implemented in the SN54LS673J?

The MR pin on the SN54LS673J is an active-low asynchronous reset that forces all 16 internal flip-flops to logic low regardless of clock or load state. It overrides all other inputs, including LOAD and CLK, and requires no setup/hold timing. This behavior is verified in the SDLS195 functional description and enables immediate fault recovery in safety-critical applications such as flight control BIT sequences or radiation-event response protocols.