DM74LS138M

Overview

The DM74LS138M is a Schottky-clamped 3-to-8 line decoder/demultiplexer manufactured by onsemi (formerly Fairchild). It operates within a supply voltage range of 4.75 V to 5.25 V and supports an operating temperature range of 0°C to +70°C. The device features three enable inputs and three binary select inputs to decode one-of-eight lines. Propagation delay times range from 18 ns to 40 ns depending on the signal path and load capacitance. It is housed in a 16-Lead Small Outline Integrated Circuit (SOIC) package.

Feature Summary

• Incorporates three enable inputs to simplify cascading and data reception applications
• Features fully buffered inputs presenting only one normalized load to the driving circuit
• Utilizes Schottky clamping for high performance and to suppress line-ringing

Applications

• High-performance memory decoding systems
• Data routing and transmission systems
• Demultiplexing applications using enable inputs as data lines

Procurement Notes

Verify component authenticity through authorized channels, as the datasheet indicates life support restrictions. Confirm RoHS compliance status with the supplier, as distributor listings may vary. Ensure the SOIC-16 package matches design requirements. Check for specific ordering suffixes if tape and reel packaging is required instead of standard tube packaging.

Selection Notes

Select this component for designs requiring low propagation delays in memory decoding or data routing. The LS logic family offers a balance of speed and power dissipation suitable for general-purpose digital systems. Verify that the 5V supply voltage aligns with system constraints. Consider the 16-pin SOIC footprint for PCB layout compatibility.

Part Context

This part belongs to the 74LS series of logic integrated circuits, specifically designed for high-speed applications. The DM74LS138 is functionally equivalent to other industry-standard 3-to-8 decoders but utilizes Schottky technology for improved switching speeds. It is often used in conjunction with other 74LS components to build complex digital logic systems.

Replacement Considerations

Compatible substitutes include MC74LS138 and SN74LS138. Verify pinout compatibility and electrical characteristics such as propagation delay and output current before substitution.