SN74HC138NS

Overview

The SN74HC138NS is a Texas Instruments SNx4HC138 device, a 3-to-8 decoder and demultiplexer housed in a 16-pin SO (Small Outline) package. It operates within a supply voltage range of 2 V to 6 V and supports an operating temperature from -40°C to +85°C. The component features three binary inputs (A, B, C) that select one of eight active-low outputs (Y0 through Y7). It incorporates three enable inputs: two active-low (G2A, G2B) and one active-high (G1), which facilitate cascading and data routing applications.

Feature Summary

• Designed for high-speed memory decoding and data transmission systems with minimal propagation delay impact.
• Outputs can drive up to 10 LSTTL loads while maintaining low power consumption.
• Incorporates three enable inputs to simplify system expansion and reduce the need for external logic gates.

Applications

• LED Displays
• Servers
• White Goods

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current Package Option Addendum to confirm production status and lead finish specifications. Confirm RoHS compliance and moisture sensitivity level requirements prior to integration. Ensure the selected variant matches the required thermal resistance and packaging quantity constraints for the target assembly process.

Selection Notes

Select this component when a standard HC-series 3-to-8 decoder is required in a surface-mount SOIC-style footprint. Verify that the 2 V to 6 V operating voltage aligns with the system power rails. Consider the maximum propagation delay characteristics relative to the memory access times or data routing speeds required by the application design.

Part Context

This part belongs to the SNx4HC138 family of decoders and demultiplexers manufactured by Texas Instruments. The 'NS' suffix specifically denotes the 16-pin Small Outline (SO) package variant. This family is designed to minimize system decoding effects in high-performance environments where fast enable circuits are utilized alongside high-speed memories.

Replacement Considerations

SN74HC138DR

FAQ

How many enable inputs does the SN74HC138NS have?

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

What is the logic state of the outputs when enabled?

The outputs are active-low; the selected output is pulled LOW while all other outputs remain HIGH.