74F521SC

Overview

The Fairchild Semiconductor 74F521SC is an expandable 8-bit magnitude comparator belonging to the 74F logic family. It compares two 8-bit binary words and provides a LOW output when the inputs match bit-for-bit. The device operates within a supply voltage range of 4.5V to 5.5V. It features active-low outputs for equality, greater-than, and less-than comparisons. The component is housed in a 20-SOIC package with a width of 7.50mm and supports surface mount mounting. It is rated for operation from 0°C to 70°C.

Feature Summary

• Performs 8-bit magnitude comparison between two binary words
• Provides distinct active-low outputs for equality, greater-than, and less-than conditions
• Supports expansion for multi-word comparison via dedicated cascade pins

Applications

• Digital data validation systems
• Address decoding circuits
• Comparator-based control logic

Procurement Notes

Verify the specific suffix 'SC' confirms the 20-SOIC package and commercial temperature range (0°C to 70°C). Confirm manufacturer origin as Fairchild Semiconductor or successor entities like ON Semiconductor, noting corporate acquisitions may affect branding on final components. Ensure datasheet revision matches design requirements.

Selection Notes

Select this component when an 8-bit magnitude comparison is required with defined propagation delays characteristic of the Fast (F) logic family. Verify that the 20-SOIC footprint fits the PCB layout constraints. Ensure the operating environment remains within the specified commercial temperature limits and that the 5V supply voltage aligns with the system power rails.

Part Context

The 74F521SC is part of the 74F series of high-speed TTL-compatible logic devices originally developed by Fairchild Semiconductor. This series was designed to offer faster switching speeds than standard 74LS logic while maintaining pin compatibility. Fairchild Semiconductor was acquired by ON Semiconductor, which continues to support and manufacture legacy parts under the ON Semi brand.

Replacement Considerations

Equivalent parts include the SN54F521J (military grade, ceramic J-package) and other 74F521 variants from manufacturers such as Texas Instruments or National Semiconductor. Verify package dimensions and electrical specifications before substitution.