MC74HCT138AN

Signal Switches, Multiplexers, Decoders Overview

The MC74HCT138AN is a high-performance silicon-gate CMOS 1-of-8 decoder/demultiplexer manufactured by onsemi. It features LSTTL-compatible inputs and operates within a supply voltage range of 4.5 V to 5.5 V. The device decodes three-bit address inputs (A0, A1, A2) into one of eight active-low outputs (Y0–Y7). It includes three chip select inputs (CS1, CS2, CS3) for cascading and demultiplexing functions. Packaged in a PDIP-16 format, it supports an operating temperature range from -55°C to +125°C.

Signal Switches, Multiplexers, Decoders Feature Summary

• Features LSTTL-compatible input levels allowing direct interfacing with TTL or NMOS outputs.
• Outputs directly interface to CMOS, NMOS, and TTL loads without additional buffering.
• Includes three chip select inputs to facilitate demultiplexing, cascading, and chip-selecting operations.

Signal Switches, Multiplexers, Decoders Applications

• Demultiplexing data streams using address inputs and chip selects.
• Cascading multiple decoder units for expanded address decoding.
• Level conversion between TTL/NMOS outputs and High-Speed CMOS inputs.

Signal Switches, Multiplexers, Decoders Procurement Notes

Verify the specific package suffix 'N' corresponds to the PDIP-16 configuration required for your design. Confirm that the ordering suffix matches the exact pinout and mechanical dimensions specified in the datasheet's package dimensions section. Ensure compatibility with the required operating temperature range and supply voltage specifications before finalizing procurement.

Signal Switches, Multiplexers, Decoders Selection Notes

Select this component when LSTTL-compatible logic levels are required for seamless integration with legacy TTL systems. The wide operating temperature range makes it suitable for industrial environments. Consider the PDIP-16 package if through-hole mounting is necessary for the application board layout.

Signal Switches, Multiplexers, Decoders Part Context

This part belongs to the MC74HCT138A series of 1-of-8 decoders and demultiplexers. It shares identical pinouts with the LS138 but utilizes high-speed CMOS technology for lower power consumption and higher noise immunity. The series is designed to bridge the gap between older TTL standards and modern CMOS requirements.

Signal Switches, Multiplexers, Decoders Replacement Considerations

MC74HCT138AD

Signal Switches, Multiplexers, Decoders FAQ

How does the MC74HCT138AN handle unused inputs?

Unused inputs must always be tied to an appropriate logic voltage level, either GND or VCC, to ensure proper operation and prevent undefined states.

What is the function of the three chip select inputs?

The three chip select inputs (two active-low and one active-high) allow for cascading multiple devices, enabling chip-selecting functions, and facilitating demultiplexing by acting as data inputs.