DM74AS245WM

Overview

The DM74AS245WM is an octal bus transceiver with 3-STATE outputs manufactured by Fairchild Semiconductor. It utilizes an advanced Schottky TTL process and operates within a supply voltage range of 4.5V to 5.5V. The device features non-inverting logic, low output impedance suitable for terminated transmission lines up to 133Ω, and PNP inputs that reduce input loading. Propagation delays are specified between 2ns and 7.5ns depending on the transition direction. It is housed in a 20-Lead Small Outline Integrated Circuit (SOIC) package.

Feature Summary

• Advanced oxide-isolated, ion-implanted Schottky TTL process
• Non-inverting logic output configuration
• Low output impedance designed to drive terminated transmission lines
• PNP inputs utilized to reduce input loading

Applications

• Memory systems
• Microprocessor systems
• Asynchronous bidirectional data buses

Procurement Notes

Verify component authenticity as this part was originally produced by Fairchild Semiconductor. Confirm current availability status through authorized distributors or legacy inventory channels. Ensure the SOIC-20 package matches design requirements. Check RoHS compliance documentation if required for specific manufacturing standards. Validate datasheet revision history against production batch dates.

Selection Notes

Select this component when high-speed switching characteristics are required for 8-bit data transfer applications. The AS series offers faster propagation delays compared to standard LS or HC families. Ensure the system operates strictly within the 4.5V to 5.5V supply voltage range. Verify that the 3-STATE outputs meet the isolation requirements for shared bus architectures. Consider thermal dissipation limits inherent to the SOIC package.

Part Context

This device belongs to the 74AS logic family, known for its high-speed performance using Advanced Schottky technology. It serves as an octal transceiver, facilitating bidirectional communication between two 8-bit buses. The DM prefix typically denotes a specific manufacturer's designation within this logic family lineage.

Replacement Considerations

• DM74LS245WM
• SN74AS245N

FAQ

How is the direction of data transmission controlled?

Direction is controlled by the DIR input. A low level directs data from Bus B to Bus A, while a high level directs data from Bus A to Bus B.

What is the function of the G input?

The G input acts as an enable control. When high, it places all outputs in a high-impedance state, effectively isolating the buses regardless of the DIR setting.