SN74HCT138PWT

Overview

The SN74HCT138PWT is a 3-line to 8-line decoder/demultiplexer manufactured by Texas Instruments in the HCT logic series. It operates within a supply voltage range of 4.5 V to 5.5 V and features TTL-compatible inputs. The device provides three enable inputs to simplify cascading and data reception, with outputs capable of driving up to 10 LSTTL loads. Typical propagation delay is 17 ns at 5.5 V, with low power consumption of 80 µA maximum ICC. It is housed in a 16-pin TSSOP package.

Feature Summary

• TTL-voltage compatible inputs for direct interfacing with standard logic families
• Three enable inputs (two active-low, one active-high) to facilitate system expansion
• Designed for high-speed memory decoding and data routing applications
• Outputs can drive up to 10 LSTTL loads

Applications

• High-performance memory systems requiring short propagation delays
• Data transmission systems utilizing fast enable circuits
• Cascaded decoder configurations for expanded address decoding

Procurement Notes

Verify the specific ordering suffix 'PWR' indicates the tape-and-reel packaging variant rather than the obsolete 'PW' tube version. Confirm RoHS compliance status and lead finish details via the latest TI Package Option Addendum. Ensure the design accommodates the -40°C to +85°C operating temperature range specified for this catalog part.

Selection Notes

Select this component when TTL-compatible input levels are required alongside CMOS performance characteristics. The HCT series ensures compatibility with older TTL logic standards while offering lower power consumption. Verify that the 4.5 V to 5.5 V supply voltage range aligns with the target system's power rails before finalizing the design.

Part Context

This device belongs to the SNx4HCT138 family of 3-line to 8-line decoders. It serves as a digital logic solution for address decoding and signal routing. The HCT technology bridges the gap between legacy TTL requirements and modern CMOS efficiency, making it suitable for mixed-logic environments where interface compatibility is critical.

Replacement Considerations

SN74HCT138PWRG4 is the RoHS-compliant equivalent of the SN74HCT138PWR. SN74HCT138DR is an alternative SOIC package option from the same manufacturer.