74AC138SJ

Overview

The Fairchild Semiconductor 74AC138SJ is a high-speed CMOS 3-to-8 line decoder/demultiplexer. It operates on a single supply voltage ranging from 2.0V to 6.0V. The device features three binary select inputs and three enable inputs (two active-low, one active-high) to facilitate cascading without external inverters. Outputs are active-low with inverted logic states. It utilizes standard CMOS packaging for surface-mount applications.

Feature Summary

• High-speed CMOS technology designed for low power consumption and wide operating voltage ranges
• Three enable inputs allow flexible system expansion and data routing without additional logic gates
• Active-low outputs provide direct compatibility with various digital decoding requirements

Applications

• Memory address decoding in high-performance computing systems
• Data routing and demultiplexing in communication interfaces
• Industrial control systems requiring reliable signal selection

Procurement Notes

Verify the specific suffix 'SJ' against the official datasheet to confirm package type and tape/reel specifications. Ensure the component matches the required RoHS compliance status and moisture sensitivity level for your assembly process. Cross-reference the manufacturer part number with authorized distributors to avoid counterfeit components.

Selection Notes

Select this component when a 3-to-8 decoding function is required within a 2V to 6V supply environment. Consider the propagation delay characteristics relative to your system clock speed. Evaluate the package constraints to ensure the surface-mount footprint fits the PCB layout. Compare power dissipation requirements against other logic families if thermal management is critical.

Part Context

This component belongs to the 74AC series of logic integrated circuits, which offers improved speed over standard 74HC devices while maintaining CMOS power efficiency. The 74AC138 variant specifically addresses the need for efficient address decoding in complex digital architectures where multiple output lines must be selectively activated based on binary input codes.

Replacement Considerations

Direct substitutes include the MC74AC138D or MC74AC138N from onsemi, as Fairchild's logic division was acquired by onsemi. Other compatible alternatives may include variants from Texas Instruments or NXP that adhere to the same 74AC electrical specifications and pinout configuration.