MC74AC138MELG

Overview

The MC74AC138MELG 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 and supports an operating ambient temperature from -40°C to +85°C. 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 EIAJ package.

Feature Summary

• Demultiplexing capability with active-low mutually exclusive outputs
• Multiple input enables allowing parallel expansion to larger decoders
• High-speed CMOS logic suitable for memory chip select address decoding

Applications

• Bipolar memory chip select address decoding
• Parallel expansion to 1-of-24 or 1-of-32 decoders
• General-purpose demultiplexing applications

Procurement Notes

Verify the specific ordering suffix 'MELG' against official manufacturer documentation to confirm the exact tape-and-reel packaging quantity and lead-free status. Ensure the procurement channel sources directly from authorized distributors to guarantee authenticity and compliance with RoHS standards.

Selection Notes

Select this component when a high-speed 1-of-8 decoding function is required within the AC logic family. Consider the EIAJ package format for board layout compatibility. Verify that the application voltage falls within the 2.0 V to 6.0 V range and that the load current requirements do not exceed the 24 mA output drive capability.

Part Context

This part belongs to the MC74AC138 series, which includes variants like MC74AC138N and MC74AC138D. The 'M' suffix indicates the EIAJ-16 package, while 'EL' typically denotes tape-and-reel packaging. It is distinct from the MC74ACT138, which features TTL-compatible inputs.

Replacement Considerations

MC74AC138MEL

FAQ

How does the MC74AC138 support decoder expansion?

It allows parallel expansion to a 1-of-24 decoder using three devices or a 1-of-32 decoder using four devices and one inverter via its multiple enable inputs.

What are the logic states for the enable inputs?

The device has two active-LOW enable inputs (E1, E2) and one active-HIGH enable input (E3). All outputs remain HIGH unless E1 and E2 are LOW and E3 is HIGH.