DM74AS244N

Overview

The DM74AS244N is an eight-wide unidirectional 3-STATE bus driver/receiver in a 20-pin Plastic Dual-In-Line (PDIP) package. It utilizes an Advanced Schottky process for improved switching performance and lower power dissipation compared to standard Schottky counterparts. The device features low output impedance suitable for driving terminated transmission lines down to 133 Ω and high input impedance to minimize line loading. It operates within a supply voltage range of 4.5V to 5.5V and supports free air operating temperatures from 0°C to +70°C.

Feature Summary

• Advanced oxide-isolated, ion-implanted Schottky TTL process technology
• Functional and pin compatible with 74LS and Schottky counterpart families
• Specified to interface with CMOS logic at VOH = VCC − 2V
• Switching response specified into 500Ω resistance and 50 pF capacitance loads

Applications

• Memory system buffer interfaces
• Microprocessor system data routing
• Communication systems signal buffering

Procurement Notes

Verify the specific ordering code suffix against manufacturer documentation to confirm package type and reel configuration. The 'N' suffix denotes the 20-Lead Plastic Dual-In-Line Package (PDIP). Ensure compatibility with existing PCB footprints designed for JEDEC MS-001 standards. Confirm thermal requirements align with the specified junction-to-ambient thermal resistance values for the PDIP variant during system integration.

Selection Notes

Select this component when bidirectional control is not required, as the DM74AS244 provides unidirectional buffering only. Choose over the DM74AS240 if non-inverting logic behavior is needed, whereas the AS240 offers inverting functions. Consider the 3-STATE enable capability for bus sharing applications. Verify that the load conditions match the specified 500Ω and 50 pF testing parameters for accurate timing analysis.

Part Context

This part belongs to the Fairchild Semiconductor DM74AS family of Advance Schottky logic circuits. The family includes both inverting (DM74AS240) and non-inverting (DM74AS244) variants. These devices are designed to replace older Schottky TTL parts while offering better speed-power trade-offs. The N package variant specifically refers to the through-hole DIP construction, distinct from the surface-mount SOIC options available in the same series.

Replacement Considerations

The datasheet explicitly states functional and pin compatibility with 74LS and Schottky counterparts. Direct substitution requires verifying that the target system can accommodate the different electrical characteristics, such as higher drive current and specific input clamp voltages, inherent to the AS series compared to LS or standard S TTL.