MC74ACT646DW

Overview

The MC74ACT646DWG is an octal registered bus transceiver with three-state outputs in a 24-lead SOIC package. It operates at a supply voltage of 4.5 V to 5.5 V and features TTL-compatible inputs. The device provides independent registers for A and B buses, allowing multiplexed real-time and stored data transfers. Propagation delay from clock to bus is typically 12.0 ns at 5.0 V, while bus-to-bus delay is typically 8.5 ns. Outputs can source or sink up to 24 mA.

Feature Summary

• Provides multiplexed transmission of data directly from the input bus or internal storage registers via D-type flip-flops.
• Features independent registers for both A and B buses to support flexible data handling functions.
• Includes control circuitry that enables true or inverting data paths and three-state output isolation.

Applications

• Multiplexed real-time and stored data transfers between system buses
• Octal bus transceiver applications requiring registered data storage
• High-speed digital logic circuits utilizing TTL-compatible inputs

Procurement Notes

Verify the specific ordering suffix (e.g., DWG) against the manufacturer's current datasheet to confirm the exact package type and lead-free status. Confirm the active status of this part number as legacy products may have discontinued variants. Ensure compatibility with existing PCB footprints for the SOIC-24 configuration before procurement.

Selection Notes

Select the ACT variant specifically when TTL-compatible input thresholds are required for interfacing with legacy logic families. Verify that the 24 mA output drive capability meets the load requirements of the destination bus. Consider the propagation delay specifications relative to the system clock speed to ensure timing margins are maintained across the operating temperature range.

Part Context

This component belongs to the MC74AC/ACT646 family of octal transceivers and registers manufactured by onsemi. It is designed for high-density digital systems requiring simultaneous data transfer and storage capabilities. The device integrates control logic to manage data flow direction and register loading based on clock and enable signals.

Replacement Considerations

Texas Instruments CD74ACT646M96 is a confirmed substitute part number.

FAQ

How does the MC74ACT646 handle data transfer?

It allows multiplexed transmission of data either directly from the input bus or from the internal storage registers depending on the state of the control inputs.

What determines when data is loaded into the registers?

Data on the A or B bus is loaded into the respective registers on the low-to-high transition of the appropriate clock pin (CAB or CBA).