DM74ALS521N

Comparators Overview

The DM74ALS521N is an 8-bit identity comparator manufactured by Fairchild Semiconductor, now part of onsemi. It performs an equal-to comparison of two 8-bit words with provisions for expansion or external enabling. The device operates within a supply voltage range of 4.5V to 5.5V and features low-active outputs indicating when inputs A and B are identical. It exhibits a maximum propagation delay of 20ns at 5V with a 50pF load. The component is housed in a 20-pin DIP package and supports through-hole mounting.

Comparators Feature Summary

• Performs equality comparison between two 8-bit input words
• Provides low-active output signal when inputs match
• Supports cascading expansion for multi-word comparisons
• Allows external enabling for controlled operation

Comparators Applications

• Digital data validation circuits
• Address matching systems
• Comparator logic in industrial control panels

Comparators Procurement Notes

Verify the manufacturer status as this component is discontinued. Confirm availability from authorized distributors or surplus suppliers. Check for RoHS compliance documentation if required for specific environmental standards. Ensure the 20-pin DIP package matches your PCB footprint requirements before ordering.

Comparators Selection Notes

Select this component for legacy 74ALS series designs requiring 8-bit equality checking. Consider the 20ns propagation delay for timing constraints. Evaluate the 20-pin DIP package for through-hole assembly needs. Verify compatibility with existing 5V logic levels and TTL input characteristics.

Comparators Part Context

This part belongs to the 74ALS (Advanced Low-power Schottky) logic family, known for improved speed over standard LS devices while maintaining lower power consumption. The DM prefix typically denotes military or enhanced grade specifications in some contexts, though it is widely used across commercial variants in this series.

Comparators Replacement Considerations

The SN74ALS521N from Texas Instruments is a confirmed direct substitute. Verify pinout and electrical specifications match exactly before replacing. Other 74ALS521 equivalents may exist but require careful datasheet cross-referencing.