Texas Instruments

SN74LS138D

SN74LS138D Description

The SN74LS138D from Texas Instruments is a high-performance 3-to-8 line decoder/demultiplexer integrated circuit (IC) designed for digital logic applications. Housed in a 16-pin SOIC package, this device operates within a 4.75V to 5.25V supply range, making it compatible with standard TTL logic levels. It features active-low outputs and includes three enable inputs (two active-low and one active-high) for flexible control. With a maximum propagation delay of 21ns, the SN74LS138D ensures fast and reliable signal decoding, making it suitable for high-speed systems. Its low power consumption (400µA output high current, 8mA output low current) and wide operating temperature range (0°C to 70°C) further enhance its versatility in industrial and commercial applications.

SN74LS138D Features

• Decoder/Demultiplexer Functionality: Converts 3 binary inputs into 8 mutually exclusive active-low outputs.
• High-Speed Operation: Propagation delay of 21ns max ensures efficient performance in time-critical applications.
• Low Power Consumption: Optimized for energy efficiency with 400µA (high) and 8mA (low) output currents.
• Robust Design: ROHS3 compliant and REACH unaffected, meeting stringent environmental standards.
• Flexible Enable Inputs: Includes G1 (active-high) and G2A, G2B (active-low) for easy cascading and system integration.
• Surface-Mount Package: 16-SOIC form factor ideal for compact PCB designs.
• Wide Voltage Range: Operates reliably at 4.75V to 5.25V, compatible with TTL logic families.

SN74LS138D Applications

The SN74LS138D is widely used in digital systems requiring address decoding, data routing, or signal demultiplexing, including:

• Memory Systems: Address decoding in RAM/ROM modules.
• Microprocessor/Microcontroller Interfaces: Expanding I/O ports or peripheral selection.
• Industrial Control Systems: Logic-level translation and signal distribution.
• Communication Equipment: Multiplexing/demultiplexing in data transmission.
• Automotive Electronics: Sensor interfacing and control unit logic.

Conclusion of SN74LS138D

The SN74LS138D stands out as a reliable, high-speed decoder/demultiplexer with low power consumption, robust construction, and broad compatibility. Its flexible enable inputs and fast switching make it ideal for complex digital systems, while its surface-mount package ensures space-efficient integration. Whether for industrial automation, computing, or telecommunications, this IC delivers precision and efficiency, backed by Texas Instruments' quality assurance. A top choice for engineers seeking a balance of performance and cost-effectiveness in logic decoding solutions.