SN74AS138N-J

Overview

The SN74AS138N-J is a commercial-grade, 3-line to 8-line decoder/demultiplexer from the Texas Instruments AS logic family. It operates on a single 4.5V to 5.5V supply and features three enable inputs (G1, G2A, G2B) for cascading or data reception. The device provides eight active-low outputs selected by binary inputs A, B, and C. It utilizes Schottky-clamped bipolar technology to achieve ultra-high speed performance with propagation delays as low as 9.5ns. The component is housed in a standard 16-pin plastic dual in-line package (PDIP).

Feature Summary

• Designed specifically for high-speed memory decoders and data transmission systems.
• Incorporates three enable inputs to simplify cascading and demultiplexing applications.
• Utilizes Schottky-clamped bipolar technology for negligible system decoding delay.

Applications

• High-performance memory decoding
• Data routing and transmission systems
• Demultiplexing applications

Procurement Notes

Verify that the ordering suffix 'J' corresponds to the ceramic chip carrier package variant rather than the standard plastic DIP. Confirm the specific datasheet revision required for your design constraints. Ensure the procurement channel sources catalog production parts. Validate RoHS compliance status if applicable to your assembly process requirements.

Selection Notes

Select this component when ultra-high speed performance is critical for memory access timing. The AS series offers significantly faster propagation delays compared to ALS variants. Verify that the 0°C to 70°C operating temperature range meets your environmental specifications. Consider the 16-pin PDIP form factor for through-hole mounting requirements.

Part Context

This part belongs to the Texas Instruments SN54/74AS138 family of 3-line to 8-line decoders. The 'SN74' prefix indicates commercial grade operation, while the 'AS' suffix denotes the ultra-high-speed bipolar technology. The '-J' suffix typically identifies the ceramic package option within the broader product line.

Replacement Considerations

SN74ALS138N

FAQ

What is the function of the three enable inputs?

The three enable inputs (one active-high G1 and two active-low G2A, G2B) allow for easy expansion into larger decoders without external inverters and can be used as data inputs for demultiplexing.

How does the output state behave when enabled?

When enabled, exactly one of the eight outputs goes low corresponding to the binary address on inputs A, B, and C, while all other outputs remain high.