SN74F138NSR

Overview

The SN74F138NSR is a decoder/demultiplexer integrated circuit manufactured by Texas Instruments. It belongs to the SN74F logic family and features three address inputs (A0, A1, A2) and eight active-low outputs (Y0 through Y7). The device operates within a supply voltage range of 4.5 V to 5.5 V and supports a propagation delay of approximately 9 ns at 5 V. It is housed in a 16-pin SOIC package designed for surface-mount technology applications.

Feature Summary

• Provides decoding functionality from three binary address lines to eight distinct active-low output lines
• Includes dedicated enable inputs that allow cascading multiple units or system-level control
• Delivers high-speed switching performance characteristic of the F logic series

Applications

• Address decoding in microprocessor-based systems
• Demultiplexing data streams in digital communication circuits
• Generating specific chip select signals for memory arrays

Procurement Notes

Verify the suffix 'SR' indicates tape-and-reel packaging when sourcing components. Confirm the manufacturer designation as Texas Instruments to ensure compatibility with standard 74F specifications. Cross-reference the datasheet for exact pinout configurations and electrical limits before integration into final designs.

Selection Notes

Select this component when active-low decoding is required for three-bit addresses. Ensure the design environment accommodates the 4.5 V to 5.5 V operating range. Consider the SOIC package dimensions for PCB layout constraints and verify thermal requirements against the specified operating temperature range.

Part Context

This part is a member of the SN74F series, known for high-speed operation compared to standard TTL logic. It serves as a functional equivalent to other industry-standard 3-to-8 line decoders. The device is widely used in general-purpose digital logic applications requiring reliable signal routing and address selection.

Replacement Considerations

Compatible substitutes include the SN74LS138 for lower speed requirements and the SN74HC138 for CMOS compatibility. Verify pinout consistency and electrical characteristics such as drive current and propagation delay when transitioning between different logic families.