SN74AS138NSR

Overview

The SN74AS138NSR is a high-speed silicon-gate AS Logic device manufactured by Texas Instruments. It functions as a 3-to-8 line decoder/demultiplexer housed in a 16-pin SOIC package. The component operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range of 0°C to +70°C. Key electrical characteristics include a propagation delay of 20 ns, with output currents rated at 400 µA for high state and 8 mA for low state.

Feature Summary

• Provides decoding or demultiplexing functionality from three binary inputs to eight active-low outputs
• Features two enable inputs that must be satisfied simultaneously for proper operation
• Utilizes high-speed silicon-gate CMOS technology for rapid signal processing

Applications

• Address decoding for memory systems
• Demultiplexing data streams in digital circuits
• Control logic in industrial automation equipment

Procurement Notes

Verify the specific suffix 'NSR' corresponds to the tape-and-reel packaging format required for automated assembly processes. Confirm that the AS logic family specifications align with the target system's voltage and speed requirements before finalizing procurement orders.

Selection Notes

Select this component when high-speed decoding is required within a standard 5V logic environment. The AS series offers superior speed compared to standard HC logic but consumes more power. Ensure the design accommodates the specific current drive capabilities and thermal constraints associated with the AS family.

Part Context

This part belongs to the Texas Instruments SN74ASxx series, which represents a high-performance subset of the broader 7400-series logic family. The SN74AS138 specifically addresses applications requiring fast decoding with active-low outputs, distinguishing it from non-inverting buffers or standard NAND gates found in other series variants.

Replacement Considerations

Compatible substitutes include the SN74LS138 for lower-speed applications or the SN74HC138 for CMOS compatibility. Verify pinout consistency and electrical parameter alignment when transitioning between these alternative logic families.