SN74HC138DR

Overview

The SN74HC138DR is a single 3-to-8 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 active-low outputs. The device incorporates three enable inputs (one high-active, two low-active) to simplify cascading or data reception. Designed for high-performance memory decoding and data-routing applications requiring short propagation delays, it can drive up to 10 LSTTL loads with typical propagation delay times as low as 15 ns.

Feature Summary

• Designed specifically for high-speed memory decoders and data-transmission systems
• Incorporates three enable inputs to simplify cascading or data reception
• Outputs can drive up to 10 LSTTL loads

Applications

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

Procurement Notes

Verify the specific ordering suffix 'DR' corresponds to the SOIC-16 package with tape-and-reel carrier configuration. Confirm RoHS compliance status and lead finish details against the latest TI Package Option Addendum. Ensure the procurement matches the required operating temperature range of -40°C to +85°C for the SN74HC138 series.

Selection Notes

Select this component when a 3-to-8 decoding function is required within standard CMOS logic families. It is suitable for designs needing wide voltage operation between 2 V and 6 V. Consider its active-low output state and enable pin logic for system integration. Verify that the SOIC-16 package dimensions fit the PCB layout constraints.

Part Context

This part belongs to the SNx4HC138 family of 3-line to 8-line decoders and demultiplexers. It utilizes CMOS technology to provide balanced output drive capabilities. The device is intended to minimize system decoding effects in high-performance memory systems where decoder delay must be negligible compared to memory access time.

Replacement Considerations

SN74HC138DRE4

FAQ

How many enable inputs does the SN74HC138DR have?

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

What is the logic state of the selected output?

The selected output is pulled LOW, while all other outputs remain HIGH.