MC74ACT640NG

Overview

The MC74ACT640NG is an octal bus transceiver from the 74ACT logic series, manufactured by onsemi. It features eight bidirectional data paths with inverted outputs and three-state capability. The device operates within a supply voltage range of 4.5 V to 5.5 V. It utilizes a 20-pin Plastic Dual In-Line Package (PDIP) for through-hole mounting. Key electrical parameters include a maximum propagation delay of 9 ns at 50 pF load capacitance, and output drive currents of 24 mA for both sourcing and sinking. The input levels are TTL compatible, while outputs provide CMOS levels.

Feature Summary

• Three-state outputs allow isolation from the bus when disabled, preventing signal interference during multi-driver operations.
• TTL-compatible inputs enable direct interfacing with standard TTL logic circuits without additional level shifting components.
• Bidirectional data flow supports flexible system architectures where data direction can be controlled via a single direction control pin.

Applications

• Memory and address bus driving in microprocessor-based systems
• Clock distribution networks requiring high fan-out capabilities
• Bus-oriented applications necessitating tri-state isolation

Procurement Notes

Verify the specific suffix 'NG' corresponds to the PDIP-20 package configuration required for your design. Confirm RoHS compliance status as manufacturing processes may vary by production batch. Check for obsolescence notices, as this component has been marked as discontinued in some distributor records. Ensure lead times align with project schedules given potential availability constraints for legacy packages.

Selection Notes

Select this component when an octal transceiver with inverted polarity is required for 5V logic systems. The ACT series offers speed comparable to LS-TTL with lower power consumption than standard TTL. Consider the PDIP package only if through-hole assembly is mandated; otherwise, evaluate SOIC alternatives like the MC74ACT640DWR2G for surface-mount designs. Verify that the 24 mA drive current meets the load requirements of the connected bus lines.

Part Context

This part belongs to the 74ACT family of advanced CMOS logic devices, designed to bridge the performance gap between low-power CMOS and high-speed TTL. The 74ACT640 specifically serves as an octal buffer/transceiver, functionally similar to the AC series but with improved switching speeds. It is often used in conjunction with other 74ACT components to build complex digital interfaces in industrial and consumer electronics.

Replacement Considerations

The MC74ACT640DWR2G is a surface-mount equivalent in the same logic family. For non-inverting applications, the MC74ACT641 series may serve as a functional alternative. Verify pinout compatibility before substituting, as package differences may require PCB layout adjustments.