DM74LS240WM

Overview

The DM74LS240WM is an octal 3-state buffer and line driver manufactured by onsemi, originally designed by Fairchild Semiconductor. It operates within a supply voltage range of 4.75V to 5.25V and supports a free air operating temperature from 0°C to +70°C. The device features inverting outputs with a typical propagation delay of 10.5ns at VCC=5V and 25°C. It provides a typical low-level sink current of 24mA and a high-level source current of -15mA. The component is housed in a 20-lead Small Outline Integrated Circuit (SOIC) package.

Feature Summary

• Features PNP data inputs that reduce DC loading on bus lines while providing improved noise rejection through hysteresis.
• Provides 3-state outputs capable of driving bus lines directly or terminated transmission lines down to 133Ω.

Applications

• Memory-address drivers
• Clock drivers
• Bus-oriented transmitters and receivers

Procurement Notes

Verify the manufacturer origin as this part was originally produced by Fairchild Semiconductor before acquisition by onsemi. Confirm the specific package variant matches the M20B designation for the 20-lead SOIC form factor. Ensure design-in compliance with the recommended operating conditions regarding supply voltage limits and thermal management requirements.

Selection Notes

Select this component when designing systems requiring octal buffering with active drive capabilities and high fanout. The inclusion of input hysteresis makes it suitable for noisy environments where signal integrity is critical. Consider the 3-state control logic for multiplexed bus architectures requiring direct line interfacing.

Part Context

This device belongs to the 74LS series of logic integrated circuits, specifically functioning as an octal buffer. It is closely related to the non-inverting DM74LS241 model. Both devices share identical pinouts and electrical characteristics but differ in logical inversion, allowing flexibility in digital circuit topology design.

Replacement Considerations

Direct substitutes include the DM74LS241 for non-inverting applications and other 74LS-series octal buffers such as the SN74LS240 from Texas Instruments. Verify pin compatibility and electrical specifications match the original design constraints.

FAQ

What is the purpose of the hysteresis feature in this device?

Hysteresis at the data inputs improves noise margins and enhances noise rejection capabilities for reliable signal processing.

Can this device drive terminated transmission lines?

Yes, the device is designed to drive terminated lines down to an impedance of 133Ω.