DM74AS240WMX

Overview

The DM74AS240WMX is an octal buffer and line driver manufactured by onsemi, utilizing the Advanced Schottky (AS) logic family. It features eight inverting outputs with three-state control, packaged in a 20-lead Small Outline Integrated Circuit (SOIC). The device operates within a supply voltage range of 4.5 V to 5.5 V. Key electrical parameters include a maximum propagation delay of 6.5 ns at VCC = 4.5V to 5.5V, a high-level output current capability of -15 mA, and a low-level output current capability of 64 mA. The component supports a free air operating temperature range from 0°C to +70°C.

Feature Summary

• Advanced oxide-isolated, ion-implanted Schottky TTL process for improved switching performance and reduced power dissipation compared to standard Schottky counterparts.
• Functional and pin-compatible with 74LS and Schottky counterpart devices, facilitating direct upgrades in existing designs.
• Low output impedance sufficient to drive terminated transmission lines down to 133 Ω without significant loading.
• Specified to interface directly with CMOS logic families at VOH = VCC − 2V.

Applications

• Memory systems requiring bus buffering
• Microprocessor system interfaces
• Communication systems utilizing bidirectional or unidirectional data buses

Procurement Notes

Verify that the ordering code includes the 'X' suffix to confirm the tape and reel packaging format, as opposed to tube packaging. Confirm the manufacturer origin, noting historical Fairchild Semiconductor documentation now falls under onsemi. Ensure the specific SOIC package dimensions match the JEDEC MS-013 standard for proper PCB footprint compatibility during procurement.

Selection Notes

Select this component when designing systems requiring high-speed buffering with low power consumption relative to standard Schottky logic. It is suitable for applications needing to drive terminated transmission lines or interface between TTL and CMOS domains. Consider the 20-lead SOIC package constraints and the specific 4.5V to 5.5V supply voltage requirements for optimal operation.

Part Context

This part belongs to the DM74AS240/DM74AS244 family of 3-State Bus Drivers/Receivers. While the DM74AS240 provides inverting buffers, the DM74AS244 offers non-inverting configurations. Both share identical pinouts and electrical characteristics, allowing them to be used interchangeably based on signal inversion requirements within memory, microprocessor, and communication architectures.

Replacement Considerations

SN74AS240AN (Texas Instruments)

FAQ

What is the maximum propagation delay for the DM74AS240WMX?

The maximum propagation delay is 6.5 ns when measured from input A to output Y at a supply voltage of 4.5V to 5.5V.

How does the DM74AS240 handle transmission line driving?

The circuit features low output impedance capable of driving terminated transmission lines down to 133 Ω, while maintaining high input impedance to avoid significant line loading.