SN74LS138NG4

Overview

The SN74LS138NG4 is a 3-to-8 line decoder and demultiplexer from the Texas Instruments SN series. It operates within a supply voltage range of 4.75 V to 5.25 V. The device features three address inputs and eight active-low outputs, with propagation delay typically specified at 41 ns. It supports a maximum clock frequency of 35 MHz and includes three enable inputs for chip selection. The component is housed in a 16-pin SOIC package, suitable for surface mount applications, and functions as a single circuit logic IC.

Feature Summary

• Provides decoding and demultiplexing functionality via three address lines controlling eight distinct output channels.
• Incorporates three independent enable inputs to manage chip activation states effectively.
• Outputs are active-low, ensuring only one channel is asserted low while others remain high during operation.

Applications

• Address decoding in microprocessor-based systems
• Data distribution in digital communication circuits
• Control signal generation for peripheral devices

Procurement Notes

Verify the specific suffix 'G4' against official Texas Instruments documentation to confirm RoHS compliance status and manufacturing origin. Ensure the ordering part number matches the exact package type and temperature grade required for your design. Cross-reference with current datasheets to validate pinout compatibility and electrical characteristics before finalizing procurement.

Selection Notes

Select this component when designing systems requiring reliable 3-to-8 line decoding within standard TTL voltage limits. Consider the LS logic family characteristics regarding power consumption and speed relative to other available options. Verify that the SOIC package dimensions fit the intended PCB layout constraints and thermal management requirements.

Part Context

This part belongs to the widely used 74LS138 family of decoders, established for general-purpose digital logic applications. It serves as a foundational component in legacy and modern mixed-signal designs where deterministic address mapping is necessary. The SN series designation indicates its classification within Texas Instruments' standard logic product portfolio.

Replacement Considerations

SN74LS138D

FAQ

What is the logic state of the outputs when the chip is enabled?

When enabled, exactly one output is driven low corresponding to the binary address input, while the remaining seven outputs remain high.

How many enable inputs does the SN74LS138NG4 have?

The device features three enable inputs (G1, G2A, G2B) that must be configured correctly to activate the decoder.