DM74S138N

Overview

The DM74S138N is a Schottky-clamped decoder/demultiplexer from the Fairchild Semiconductor DM74S series. It decodes one-of-eight lines based on three binary select inputs and three enable inputs. The device features two active-LOW and one active-HIGH enable inputs to simplify cascading and data reception applications.

Feature Summary

• Schottky clamping for high performance
• Fully buffered inputs presenting only one normalized load
• Three enable inputs to simplify cascading

Applications

• High-performance memory decoding
• Data routing applications
• Data transmission systems

Procurement Notes

Verify the specific package variant against the ordering code, as the N suffix typically denotes a plastic dual-in-line package. Confirm that the component meets the required environmental specifications and check for any obsolete status or lifecycle restrictions before finalizing procurement plans.

Selection Notes

Select this component when short propagation delay times are critical for system performance. The inclusion of multiple enable inputs reduces the need for external gates during expansion. Ensure the design utilizes the fully buffered inputs to minimize loading effects on the driving circuit.

Part Context

This part belongs to the DM74S family of Schottky TTL logic devices. These circuits are designed for high-speed applications where low power dissipation and fast switching response are required. The family includes various decoders and demultiplexers optimized for memory systems.

Replacement Considerations

Check for pin-compatible alternatives within the same logic family. Verify that substitute components maintain the Schottky clamping characteristics and enable input configurations required for the existing system design.