SN74HCT138NG4

Overview

The SN74HCT138NG4 is a 3-line to 8-line decoder/demultiplexer from the Texas Instruments SNx4HCT138 family. It operates within a supply voltage range of 4.5 V to 5.5 V and features TTL-compatible inputs with low input current (1 µA max). The device provides three enable inputs to simplify cascading and demultiplexing applications. Typical propagation delay is 17 ns at 5 V, with outputs capable of driving up to 10 LSTTL loads or ±4 mA at 5 V. Maximum supply current is 80 µA.

Feature Summary

• TTL-voltage compatible inputs for direct interfacing with standard logic systems
• Three enable inputs allowing simplified expansion and data reception control
• Low power consumption with minimal supply current requirements
• High-speed performance suitable for memory decoding and data routing

Applications

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

Procurement Notes

Verify that the ordering suffix 'G4' corresponds to lead-free packaging and RoHS compliance as indicated in manufacturer documentation. Confirm package type availability matches design requirements, as this part number typically denotes specific manufacturing revisions or environmental certifications within the HCT138 series. Cross-reference official datasheets for exact mechanical dimensions and thermal characteristics before finalizing procurement specifications.

Selection Notes

Select this component when TTL-compatible logic levels are required alongside high-speed decoding capabilities. The HCT series ensures compatibility with standard 5 V TTL systems while offering lower power consumption than older technologies. Ensure the application benefits from the specific enable pin configuration for system expansion or demultiplexing needs without requiring additional external gates.

Part Context

This device belongs to the SNx4HCT138 family of 3-line to 8-line decoders and demultiplexers manufactured by Texas Instruments. The family includes variants such as SN74HCT138N and SN74HCT138D, differing primarily in package style and operating temperature ranges. The HCT logic family is characterized by CMOS technology with TTL-compatible input thresholds, bridging the gap between legacy TTL systems and modern low-power CMOS designs.

Replacement Considerations

SN74HCT138N serves as a direct functional equivalent within the same product family. Verify package compatibility and ensure that any substitute maintains the required 4.5 V to 5.5 V operating voltage range and TTL input compatibility for seamless integration into existing circuit designs.