MC74AC138NG

Overview

The MC74AC138NG is a high-speed 1-of-8 decoder/demultiplexer manufactured by onsemi. It accepts three binary weighted inputs (A0, A1, A2) and provides eight mutually exclusive active-LOW outputs (O0-O7). The device operates within a supply voltage range of 2.0 V to 6.0 V. It features three enable inputs: two active-LOW (E1, E2) and one active-HIGH (E3). Outputs can source or sink up to 24 mA. The component is housed in a 16-lead PDIP package.

Feature Summary

• Demultiplexing capability using enable inputs as data strobes
• Multiple input enables allow parallel expansion to larger decoders
• Active LOW mutually exclusive outputs

Applications

• High-speed bipolar memory chip select address decoding
• Parallel expansion to 1-of-24 or 1-of-32 decoders
• General-purpose 1-of-8 decoding

Procurement Notes

Verify the specific ordering suffix 'N' corresponds to the PDIP-16 package configuration required for your design. Confirm RoHS compliance status with the manufacturer, as standard and Pb-free devices share specifications but may have distinct orderable part numbers. Ensure the selected variant matches the lead-free requirements of your assembly process.

Selection Notes

Select this component when a high-speed CMOS decoder with wide voltage operation is needed. The AC series offers faster performance than standard HC logic. Consider the ACT variant if TTL-compatible input thresholds are strictly required for interfacing with legacy systems. Verify that the 24 mA output drive current meets the load requirements of the connected circuitry.

Part Context

This device belongs to the MC74AC138 family of 1-of-8 decoders and demultiplexers. It is functionally compatible with other industry-standard 74AC138 parts. The 'AC' designation indicates Advanced CMOS technology, providing higher speed and lower power consumption compared to older NMOS or standard CMOS equivalents. It is designed for general-purpose digital logic applications requiring address decoding.

Replacement Considerations

MC74AC138D

FAQ

How many enable inputs does the MC74AC138NG have?

It has three enable inputs: two active-LOW inputs (E1, E2) and one active-HIGH input (E3).

Can the MC74AC138NG be used as a demultiplexer?

Yes, it can be used as an 8-output demultiplexer by using one of the active LOW Enable inputs as the data input and the other Enable inputs as strobes.