74HCT646D,653

Overview

The 74HCT646D,653 is an octal bus transceiver and register featuring three-state outputs. It operates within a supply voltage range of 4.5 V to 5.5 V. The device supports bidirectional data transfer between two buses. It includes a clock input for latching data into the internal register. The component utilizes HCT logic levels, ensuring compatibility with TTL-driven systems. It is housed in a standard surface-mount package suitable for automated assembly processes.

Feature Summary

• Octal configuration providing eight independent data paths
• Three-state outputs allowing direct connection to system buses
• Bidirectional data transfer capability between two buses
• Clock-controlled data latching for synchronous operation

Applications

• System memory addressing
• Carriage control in printing equipment
• Signal buffering on microprocessor-based systems

Procurement Notes

Verify the specific ordering code suffix against official NXP documentation to confirm package type and tape-and-reel specifications. Ensure the requested variant matches the required industrial or automotive qualification standards if applicable. Cross-reference the manufacturer part number with authorized distributor catalogs to confirm current production status and availability constraints before finalizing procurement orders.

Selection Notes

Select this component when an octal buffer or register with three-state outputs is required for bidirectional data transmission. The HCT technology ensures compatibility with standard TTL logic families while offering CMOS noise immunity. Consider the operating temperature range and package dimensions during PCB layout planning to ensure proper thermal management and mechanical fit within the target enclosure design.

Part Context

This component belongs to the 74HCT series of high-speed CMOS logic devices manufactured by NXP Semiconductors. The series is designed for applications requiring compatibility with TTL logic levels. The 74HCT646 specifically functions as an octal bus transceiver, providing essential interface capabilities in digital systems. It represents a standard solution for data routing and storage in complex electronic architectures.

Replacement Considerations

Compatible substitutes include other octal bus transceivers from the 74HCT family, such as the 74HCT245 or 74HCT165. Verify pinout compatibility and electrical characteristics before substitution. Alternative manufacturers may offer equivalent parts, but functional equivalence must be confirmed through detailed datasheet comparison.