MC74ACT138M

Overview

The MC74ACT138M is a 3-to-8 line decoder and demultiplexer manufactured by onsemi, originally under the Motorola brand. It operates within a supply voltage range of 4.5 V to 5.5 V. The device features three binary address inputs (A0, A1, A2) and eight active-low outputs. It includes three enable inputs: two active-low (G1, G2) and one active-high (G3), facilitating cascading applications. The component is housed in a 16-pin SOIC package and supports surface-mount installation.

Feature Summary

• Provides decoding of three binary bits into eight mutually exclusive active-low outputs
• Includes multiple enable inputs to manage chip selection and simplify system expansion
• Compatible with standard CMOS logic families while offering performance comparable to Schottky TTL

Applications

• Memory address decoding in computer systems
• Data routing and distribution networks
• Demultiplexing control signals for peripheral devices

Procurement Notes

Verify the manufacturer designation carefully, as Motorola's semiconductor division was acquired by onsemi. Ensure the part number suffix matches the required package type and tape/reel specifications for your assembly process. Confirm RoHS compliance status if environmental regulations apply to your specific manufacturing region or end-use product requirements.

Selection Notes

Select this component when a high-speed 3-to-8 decoder is required with low power consumption characteristics typical of CMOS technology. It serves as a direct functional replacement for older 74LS138 designs where lower power dissipation is critical. Consider the operating temperature range and package availability relative to your PCB layout constraints and thermal management needs.

Part Context

This device belongs to the 74ACT logic family, which bridges the performance gap between standard CMOS and Low-Power Schottky TTL. It maintains pin compatibility with previous generations while improving switching speeds and reducing power usage. The MC74ACT138M represents a mature, widely adopted solution for digital logic decoding tasks in industrial and commercial electronics.

Replacement Considerations

Direct substitutes include MC74ACT138DR2G and CD74ACT138M96. Verify that alternative sources maintain identical pin configurations and electrical characteristics to ensure seamless integration without circuit redesign.