DM74LS155N

Overview

The DM74LS155N is a dual 2-line to 4-line decoder/demultiplexer in the 74LS TTL logic family. It features two independent sections with common binary-address inputs (A, B) and individual strobes (G1, G2). Data input C1 provides inverted outputs, while C2 provides true outputs. The device operates at a supply voltage of 4.75V to 5.25V. Propagation delays range from 18ns to 35ns depending on the input path. It utilizes a 16-lead Plastic Dual-In-Line Package (PDIP) suitable for through-hole mounting.

Feature Summary

• Dual configuration allows simultaneous decoding or demultiplexing operations within a single package
• Individual strobe inputs enable selective activation or inhibition of each 4-bit section
• Input clamping diodes minimize transmission-line effects and simplify system design
• Totem-pole output structure supports standard digital logic interfacing

Applications

• Dual 2-to-4-line decoding
• Dual 1-to-4-line demultiplexing
• Cascaded 3-to-8-line decoding configurations
• Cascaded 1-to-8-line demultiplexing applications

Procurement Notes

Verify component authenticity and datasheet revision status prior to integration. Confirm that the PDIP-16 package dimensions match the target PCB footprint. Ensure operating temperature ranges align with environmental requirements. Check for end-of-life status as this component may be discontinued by the manufacturer.

Selection Notes

Select this component when dual independent decoding paths are required in a compact form factor. The LS series offers a balance of speed and power consumption suitable for general-purpose digital systems. Consider the DM74LS156 if open-collector outputs are preferred over the totem-pole structure provided by the DM74LS155.

Part Context

This device belongs to the Fairchild Semiconductor DM74LS series, which implements Low-power Schottky TTL technology. The series is characterized by reduced power dissipation compared to standard TTL while maintaining compatible switching speeds. The DM74LS155 specifically addresses applications requiring multiple decoding functions without consuming excessive board space.

Replacement Considerations

Direct pin-compatible substitutes include the DM74LS156, which shares the same package and pinout but features open-collector outputs instead of totem-pole outputs. Designers must verify output drive requirements when selecting between these variants.