Texas Instruments SN54F138J

Overview

SN54F138J from Texas Instruments is a military-grade 3-line to 8-line decoder/demultiplexer in a 16-pin CDIP package, featuring dual active-low (G2A, G2B) and single active-high (G1) enable inputs, propagation delays as low as 2.7 ns (tPLH), and operation across –55°C to 125°C for high-speed memory decoding in avionics and defense systems.

For engineers reviewing the SN54F138J datasheet, SN54F138J pinout, SN54F138J application, or SN54F138J equivalent, key selection criteria include its triple-enable architecture for cascaded decoding, guaranteed military-temperature performance, TTL-compatible input thresholds, and direct demultiplexing capability using G2A/G2B as data inputs.

Technical Context

The SN54F138J implements positive-logic decoding with three binary select inputs (A, B, C) and three independent enables (G1, G2A, G2B), where outputs Y0–Y7 are active-low and mutually exclusive. Its logic diagram confirms NAND-based output generation with no internal inversion on select lines.

It supports both decoder and demux modes: when G2A or G2B is used as a data input, the device routes that signal to one of eight outputs based on A/B/C, enabling 1-to-8 data distribution without external gating. All enables must be satisfied for any output to activate.

Key Specifications

Pinout & Package

SN54F138J is supplied in a 16-pin Ceramic Dual-In-Line Package (CDIP, J package), with 0.3-inch body width, through-hole mounting, and hermetic sealing suitable for high-reliability applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder/demultiplexer applications.

Compared with SN54F138J, SNJ54F138J offers identical performance and form factor but reflects TI's internal part-numbering convention, while 5962-9758201QEA delivers the same silicon in a QML-qualified configuration with enhanced traceability for defense prime contracts.

Availability

SN54F138J is available at Aetrix Electronics and suitable for avionics address decoding, secure communication module control, and ruggedized test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN54F138J 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.

The SN54F138J belongs to TI's military 74F logic family, engineered for high-speed, low-latency decoding in defense, aerospace, and industrial systems where timing predictability and environmental robustness are non-negotiable.

FAQ

What is the maximum operating temperature range for the SN54F138J?

The SN54F138J is characterized for operation from –55°C to 125°C, meeting MIL-PRF-38535 requirements for military-grade logic devices. This full-range qualification ensures reliable performance in extreme environments such as aircraft bays, missile guidance systems, and ground vehicle engine compartments. The SN54F138J maintains specified propagation delays and output drive strength across this entire span without derating.

Can the SN54F138J be used as a demultiplexer, and how is that configured?

Yes, the SN54F138J supports demultiplexing by using either G2A or G2B as the data input while holding the other enable and G1 constant, and applying address bits to A, B, and C. For example, with G1 = H, G2B = L, and G2A as data input, the signal on G2A appears inverted on the selected Yx output. This configuration eliminates the need for additional logic gates and is explicitly supported in the device's function table and application description. The SN54F138J thus serves dual roles without external components.

What are the absolute maximum ratings for supply voltage and output current on the SN54F138J?

The SN54F138J has an absolute maximum supply voltage (VCC) of –0.5 V to 7 V and can sink up to 40 mA per output in the low state. However, the recommended operating condition specifies a maximum output sink current (IOL) of 20 mA to ensure parametric compliance across temperature. Exceeding 20 mA may cause VOL to exceed 0.5 V or induce excessive self-heating. These limits are defined in the SN54F138J datasheet's absolute maximum ratings and recommended operating conditions tables.

How does the enable structure of the SN54F138J simplify cascaded decoding?

The SN54F138J uses two active-low enables (G2A, G2B) and one active-high enable (G1), allowing direct connection to outputs of upstream decoders without inverters. For example, a 24-line decoder can be built using three SN54F138J devices with G1 driven by a common signal and G2A/G2B tied to decoded outputs - no external gates needed. This architecture reduces board area, propagation delay, and component count in multi-level memory decode trees. The SN54F138J's enable design is optimized specifically for this hierarchical use case.

Is the SN54F138J pin-compatible with commercial-grade SN74F138 variants?

No, the SN54F138J is not pin-compatible with SN74F138 variants in different packages: SN54F138J uses a 16-pin CDIP (J) package, while SN74F138N uses a 16-pin PDIP and SN74F138D uses a 16-pin SOIC - all share identical pinouts but differ in physical dimensions, thermal characteristics, and reliability screening. The SN54F138J's J-package has ceramic body and metal leads, whereas PDIP/SOIC versions use plastic bodies. Thus, mechanical replacement requires PCB redesign, though logic behavior and pin functions match exactly.