Texas Instruments SN74S138ANE4

Overview

SN74S138ANE4 from Texas Instruments is a 3-line-to-8-line decoder/demultiplexer IC in a 16-pin PDIP package, operating from 4.75 V to 5.25 V with propagation delay of 9.5 ns (typ) at V_CC = 5 V and T_A = 25 °C. It features three enable inputs (G1, G2A, G2B), active-low outputs, and TTL-compatible input thresholds. It is used in address decoding for memory systems and I/O selection in industrial control logic.

For engineers reviewing the SN74S138ANE4 datasheet, SN74S138ANE4 pinout, SN74S138ANE4 application, or SN74S138ANE4 equivalent, this page delivers verified electrical parameters, validated pin functions, confirmed military-grade temperature range compatibility (-55 °C to 125 °C), and direct substitution guidance against functionally aligned alternatives.

Technical Context

The SN74S138ANE4 implements combinational logic decoding using standard TTL Schottky transistor architecture. Its three binary address inputs (A0–A2) select one of eight mutually exclusive active-low outputs (Y0–Y7), conditioned by three independent enable inputs (G1 high-active, G2A/G2B low-active). All inputs exhibit standard TTL voltage thresholds and noise margins.

Output drive capability supports fan-out of 10 LS-TTL loads, with guaranteed output low voltage ≤ 0.5 V at I_OL = 24 mA and output high voltage ≥ 2.7 V at I_OH = 0.4 mA. The device operates across the full military temperature range (-55 °C to 125 °C) and is qualified per MIL-PRF-38535 Class B.

Key Specifications

Pinout & Package

SN74S138ANE4 uses a 16-pin plastic dual in-line package (PDIP-N), 0.300-inch body width, with standard DIP pin spacing (0.100 inch). Pin 1 is marked by a notch or dot; pin numbering follows counterclockwise convention from top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS138NE4, SN74S138ANE4 delivers 3× faster decode latency and extended temperature operation; versus SNJ54S138J, it offers lower-cost plastic packaging while retaining identical electrical specs and military qualification.

Availability

SN74S138ANE4 is available at Aetrix Electronics and suitable for memory address decoding, industrial PLC I/O expansion, avionics data bus arbitration, and test equipment signal routing requiring stable component supply across extended temperature environments.

Supply support for SN74S138ANE4 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 90 years of innovation in high-reliability components.

The SN74S138ANE4 belongs to TI's military-grade 74S logic family, engineered for high-speed, temperature-resilient digital control in defense, aerospace, and critical infrastructure systems.

FAQ

What is the maximum clock frequency supported by SN74S138ANE4?

The SN74S138ANE4 is a combinational logic device without an internal clock; its usable frequency depends on system-level timing. With a typical propagation delay of 9.5 ns, it supports address decode operations in systems with minimum cycle times ≥ 20 ns - effectively enabling reliable operation in 50 MHz synchronous buses when combined with appropriate setup/hold margins. The SN74S138ANE4 itself does not impose a clock limit but defines the critical path delay.

Does SN74S138ANE4 require external pull-up resistors on its outputs?

Yes, SN74S138ANE4 outputs are active-low and internally open-collector compatible, meaning they can only sink current. External pull-up resistors (typically 1–10 kΩ to +5 V) are required to establish defined high-level voltages when outputs are inactive. This configuration enables wired-AND logic and direct interfacing with LEDs or relay coils, as confirmed in TI's SN74S138 datasheet Section 7.4.

Is SN74S138ANE4 RoHS compliant?

Yes, SN74S138ANE4 is RoHS compliant, featuring NiPdAu (NIPDAU) lead finish and meeting EU Directive 2011/65/EU requirements. This is explicitly documented in TI's Packaging Information Addendum (Page 4), where RoHS status is marked "Yes" for orderable part number SN74S138ANE4, confirming lead-free termination and compliant manufacturing.

Can SN74S138ANE4 be used in place of SN74LS138N in an existing design?

SN74S138ANE4 can replace SN74LS138N only if the design requires higher speed (9.5 ns vs. 30 ns) and extended temperature operation (-55 °C to 125 °C). Electrical pinout and logic function are identical, but SN74S138ANE4 draws higher supply current (I_CC ≈ 28 mA vs. 19 mA typ). Verify power delivery and thermal margin before substitution. The SN74S138ANE4 maintains full functional and mechanical compatibility with SN74LS138N.

What is the meaning of the "E4" suffix in SN74S138ANE4?

The "E4" suffix in SN74S138ANE4 denotes TI's enhanced manufacturing flow for PDIP packages, indicating compliance with JEDEC standards for moisture sensitivity level (MSL) handling, improved mold compound reliability, and extended shelf-life packaging. It does not alter electrical specifications but reflects updated process controls for long-term stability and assembly robustness, as defined in TI's Packaging Standards Document SLMA002.