SN74HC138DT

Overview

The SN74HC138DT is a 3-to-8 line decoder and demultiplexer manufactured by Texas Instruments in the HC logic family. It operates within a supply voltage range of 2 V to 6 V and features three binary select inputs (A, B, C) and three enable inputs (G1, G2A, G2B). The device provides eight active-low outputs (Y0–Y7) housed in a 16-pin SOIC package with a body size of 9.90 mm x 3.90 mm. It supports an operating temperature range from -40°C to +85°C.

Feature Summary

• Designed for high-speed memory decoding and data transmission systems requiring short propagation delays
• Outputs can drive up to 10 LSTTL loads while maintaining low power consumption
• Incorporates three enable inputs to simplify cascading or data reception applications

Applications

• LED Displays
• Servers
• White Goods
• Power Infrastructure
• Building Automation

Procurement Notes

Verify current production status as the SN74HC138DT is listed as obsolete in official documentation. Confirm availability of alternative packages such as SN74HC138DR or SN74HC138PWR for ongoing projects. Ensure compliance with RoHS standards and check for updated packaging options before finalizing procurement plans.

Selection Notes

Select this component for applications requiring fast decoding with minimal system delay impact. Verify that the 2 V to 6 V supply voltage range matches the system requirements. Consider the 16-pin SOIC package dimensions for PCB layout constraints. Evaluate thermal resistance metrics if operating near maximum temperature limits.

Part Context

This part belongs to the SNx4HC138 series of 3-to-8 decoders and demultiplexers. It is designed to minimize system decoding effects in high-performance memory systems. The device uses CMOS technology and offers balanced output drive capabilities suitable for various digital logic applications.

Replacement Considerations

SN74HC138DR

FAQ

How many enable inputs does the SN74HC138DT have?

The device has three enable inputs: one active-high (G1) and two active-low (G2A, G2B).

What is the function of the enable inputs?

All three enable inputs must be active for the outputs to be enabled. Deactivating any enable input forces all outputs high.