CD74FCT646M

Overview

The CD74FCT646M is an octal registered bus transceiver manufactured by Harris Corporation, belonging to the FCT logic series. It features a single functional unit with eight bits per element and provides true (non-inverting) output polarity. The device utilizes a 24-pin Small Outline package (PDSO24). It operates within a supply voltage range of 4.5V to 5.5V and supports bidirectional data transmission. The component includes three-state outputs for effective bus driving and management.

Feature Summary

• Registered bus transceiver architecture supporting multiplexed transmission of registered or real-time data via dedicated select inputs.
• Direction control capability enabling bidirectional data flow between two ports.
• Three-state output configuration allowing safe connection to shared system buses.

Applications

• High-speed data acquisition systems requiring registered input buffering.
• Multiprocessor architectures utilizing bidirectional data buses.
• Memory interface circuits where data latching and direction control are required.

Procurement Notes

Verify the manufacturer origin carefully, as this component was originally produced by Harris Corporation, which has undergone corporate restructuring and acquisitions. Confirm that the specific revision matches the original Harris specifications rather than subsequent licensee versions. Check RoHS compliance status, as older Harris production runs may not meet current environmental standards. Ensure the package marking aligns with the PDSO24 form factor.

Selection Notes

Select this component when a registered transceiver with direction control is necessary for an 8-bit wide bus. The FCT series offers faster switching speeds compared to standard HCT logic. Consider the operating temperature range and ensure the power supply voltage remains strictly within the 4.5V to 5.5V limits. Verify that the load capacitance requirements of the connected lines do not exceed the specified 50 pF limit for optimal performance.

Part Context

This part belongs to the broader CD74HCT/ACT/FCT family of logic devices. While sharing similar pinouts and basic functions with non-registered variants like the CD74HCT646, the 'R' in the designation indicates internal registration capabilities. This distinguishes it from simple bus drivers, adding storage functionality to hold data states independently of input changes during specific control phases.