SN74S85N

Overview

The SN74S85N is a 4-bit magnitude comparator from the Texas Instruments S-series logic family. It compares two 4-bit binary or BCD words to determine their relative magnitude, providing active-high outputs for A>B, A=B, and A<B conditions. The device operates on a single 5V supply with a voltage range of 4.75V to 5.25V. Key electrical parameters include a maximum propagation delay of 18 ns and a maximum power supply current of 20 mA. It is housed in a standard 16-pin PDIP package suitable for through-hole mounting.

Feature Summary

• Provides three distinct active-high outputs indicating whether input A is greater than, equal to, or less than input B
• Supports cascading via dedicated inputs to facilitate multi-bit comparison expansion
• Designed for high-speed digital applications within the S-series TTL logic family

Applications

• Digital arithmetic logic units requiring magnitude determination
• Address decoding systems in computer architectures
• Control logic for sorting algorithms and data validation circuits

Procurement Notes

Verify the specific suffix against official datasheets to confirm pinout and electrical characteristics. Ensure the procurement channel provides genuine Texas Instruments components to avoid counterfeit risks. Confirm that the 16-pin DIP package aligns with your PCB footprint requirements. Check for RoHS compliance status if environmental regulations apply to your manufacturing process.

Selection Notes

Select this component when high-speed comparison is required compared to standard LS series devices. Consider the S-series speed-power trade-offs against other logic families like ALS or AS. Verify that the 5V operating voltage matches your system's power rails. Ensure the through-hole packaging is compatible with your assembly technology constraints.

Part Context

The SN74S85N belongs to the Texas Instruments SN74Sxx series, known for advanced Schottky technology. This series offers faster switching speeds than standard TTL while maintaining compatibility with existing logic interfaces. The 4-bit comparator function is a fundamental building block in digital design, often used alongside adders and subtractors for complete arithmetic operations.

Replacement Considerations

SN74LS85N: Slower speed but lower power consumption. SN74S85N-1: Verified equivalent variant with identical functionality.