DM74AS640N

Overview

The DM74AS640N is a 3-State Octal Bus Transceiver manufactured by onsemi, utilizing an advanced Schottky process. It contains eight pairs of logic elements for bidirectional data transmission between A and B buses, controlled by DIR and G inputs. The device operates within a supply voltage range of 4.5V to 5.5V and supports a free air operating temperature from 0°C to +70°C. Key electrical parameters include a propagation delay (tPLH/tPHL) of 2ns to 7ns/6ns, output drive currents of -15mA (high) and 64mA (low), and input/output levels compatible with TTL and CMOS standards.

Feature Summary

• Advanced oxide-isolated, ion-implanted Schottky TTL process for improved AC performance
• Functionally and pin-for-pin compatible with Schottky, low power Schottky, and advanced low power Schottky TTL counterparts
• Includes protection features preventing bus glitching during power-up or power-down sequences
• Low output impedance capable of driving terminated transmission lines

Applications

• Memory systems
• Microprocessor systems
• Asynchronous bidirectional data buses

Procurement Notes

Verify the specific package configuration required for your design, as this part number corresponds to the 20-Lead Plastic Dual-In-Line Package (PDIP). Confirm that the manufacturer documentation aligns with current sourcing channels, noting historical production by Fairchild Semiconductor prior to corporate restructuring. Ensure compatibility with existing system voltage and thermal requirements before finalizing procurement plans.

Selection Notes

Select this component when high-speed bidirectional data transfer is required in microprocessor or memory architectures. Its compatibility with standard Schottky logic families simplifies integration into legacy designs. Consider the PDIP package constraints regarding board space and thermal dissipation compared to surface-mount alternatives like the SOIC variant.

Part Context

This device belongs to the 74AS series of logic integrated circuits, characterized by advanced Schottky technology. It serves as an octal bus transceiver, distinct from simpler buffer or driver ICs by its dual-directional control capabilities. The N suffix specifically denotes the plastic dual-in-line package format, differentiating it from the W suffix used for small outline packages.

Replacement Considerations

SN74AS640AN