DM74AS646WM

Overview

The DM74AS646WM is an octal bus transceiver and register manufactured by onsemi, housed in a 24-lead Small Outline Integrated Circuit (SOIC) package. It operates within a supply voltage range of 4.5V to 5.5V and supports a maximum clock frequency of 90 MHz. The device features 3-state outputs with a low-level output current of 48 mA and a high-level output current of -15 mA. Propagation delays are specified at 9 ns for data transfer between buses, while storage-to-output delays reach up to 29 ns.

Feature Summary

• Integrates an octal bus transceiver with edge-triggered D-type flip-flops for multiplexed data transmission.
• Features totem-pole 3-state outputs designed to drive highly-capacitive or low-impedance loads directly.
• Includes make-before-break select controls to eliminate glitches during transitions between stored and real-time data.

Applications

• Implementing buffer registers in digital systems
• Designing I/O ports for microprocessor interfaces
• Creating bidirectional bus drivers
• Functioning as working registers in memory architectures

Procurement Notes

Verify the component status carefully, as this specific part number may be discontinued or subject to limited availability. Confirm that the SOIC-24 package matches your PCB footprint requirements. Ensure that the logic family compatibility meets your system's voltage and timing specifications before finalizing procurement plans.

Selection Notes

Select this component when an octal transceiver with internal storage capability is required. It is functionally compatible with LS TTL counterparts but offers higher speed performance due to the AS series process. Consider the 24-pin SOIC package constraints and verify that the 90 MHz clock limit satisfies your application's timing needs.

Part Context

This device belongs to the 74AS logic family, utilizing an advanced oxide-isolated, ion-implanted Schottky TTL process. It is part of a series that includes the DM74AS648, which provides inverted outputs. The component is designed for high-performance applications requiring fast switching speeds and direct bus driving capabilities without external pull-up components.

Replacement Considerations

Public confirmed substitute part numbers: SN74AS646DW (Texas Instruments).