CD74HCT251M

Overview

The CD74HCT251M is a high-speed CMOS logic device manufactured by Harris Corporation, functioning as an 8-input multiplexer with three-state outputs. It operates within a supply voltage range of 4.5V to 5.5V and supports a wide operating temperature range from -55°C to 125°C. The component is housed in a 16-pin Small Outline Integrated Circuit (SOIC) package, designed for surface-mount installation. As part of the HCT series, it utilizes TTL-compatible inputs while maintaining CMOS low power consumption characteristics.

Feature Summary

• Provides eight selectable data inputs routed to a single output based on address selection
• Features three-state output capability allowing direct bus connection without external buffers
• Ensures compatibility with standard TTL logic levels through HCT input specifications

Applications

• Data routing in digital communication systems
• Address decoding and signal selection in microprocessor interfaces
• Multiplexing multiple data sources for transmission over shared lines

Procurement Notes

Verify the manufacturer designation carefully, as Texas Instruments acquired Harris Semiconductor's logic product line. Confirm that the specific suffix 'M' corresponds to the SOIC-16 package variant. Ensure compliance with RoHS directives if required, noting that original Harris markings may differ from current TI production standards. Cross-reference datasheets to confirm pinout consistency between legacy Harris and current TI versions.

Selection Notes

Select this component when an 8-to-1 multiplexing function with tri-state output control is required in space-constrained designs. The HCT series ensures compatibility with 5V TTL logic families, simplifying interface design with older digital systems. The wide industrial temperature range makes it suitable for harsh environments where standard commercial grade parts would fail. Consider the SOIC-16 footprint for PCB layout constraints.

Part Context

This device belongs to the CD74HCTxxxyy family of high-speed CMOS logic integrated circuits originally developed by Harris Corporation before being transferred to Texas Instruments. The HCT series was engineered to bridge the gap between CMOS power efficiency and TTL noise immunity. This specific model represents the multiplexer variant within the broader logic catalog, serving critical data path management roles in embedded systems.

Replacement Considerations

• CD74HCT251ME4
• CD54HCT251