74ACT521SC

Overview

The onsemi 74ACT521SC is an 8-bit identity comparator integrated circuit housed in a 20-SOIC surface-mount package. It operates within a supply voltage range of 4.5V to 5.5V and features active-low outputs that indicate equality between two 8-bit inputs (A=B). The device provides symmetrical output drive capabilities of 24mA for both high and low states, with a maximum propagation delay of 10ns at 5V with 50pF load. Quiescent current is specified at 4µA, and it supports an operating temperature range from -40°C to +85°C.

Feature Summary

• Provides magnitude comparison functionality with active-low output assertion when input values are identical
• Features high-drive capability suitable for direct interface with TTL-compatible loads
• Supports bus sharing through defined logic states within standard CMOS families

Applications

• Digital data path validation systems requiring equality checks
• Address matching circuits in memory subsystems
• Control logic verification in industrial automation equipment

Procurement Notes

Verify component authenticity through authorized distribution channels due to obsolete status. Confirm package integrity and pin alignment against the 20-SOIC specification before integration. Review manufacturer documentation for handling precautions related to moisture sensitivity levels and electrostatic discharge protection during storage and assembly processes.

Selection Notes

Select this component for designs requiring precise 8-bit equality detection with fast response times. Ensure power supply stability within the 4.5V to 5.5V window to maintain timing specifications. Consider thermal management requirements given the operational temperature range and verify board layout compatibility with the SOIC footprint dimensions.

Part Context

This part belongs to the 74ACT series of high-speed CMOS logic devices, designed to bridge performance gaps between older TTL standards and modern CMOS technologies. The 74ACT521 specifically addresses identity comparison needs within digital logic families, offering standardized pinouts compatible with existing 74-series infrastructure while providing improved switching speeds and lower power consumption characteristics.

Replacement Considerations

Public confirmed substitute part numbers are not available as the product status is listed as obsolete.