74LCX646MTCX

Overview

The Fairchild Semiconductor 74LCX646MTCX is a low-voltage octal bus transceiver from the 74LCX logic family. It features eight non-inverting data paths with 5V tolerant inputs and outputs, enabling direct interfacing between 3.3V systems and legacy 5V devices. The device operates within a supply voltage range of 2.0V to 3.6V and supports surface-mount TSSOP-48 packaging. Key electrical specifications include a maximum propagation delay of 5.2ns at VCC=3.3V with 50pF load, and output drive currents of ±24mA. It functions as both a transceiver and register, controlled by direction (DIR) and output enable (OE) signals.

Feature Summary

• Provides bidirectional data transfer for eight-bit wide buses with simultaneous register capability
• Features 5V tolerant inputs and outputs for seamless compatibility between 3.3V and 5V logic domains
• Includes independent direction control and output enable pins for flexible bus management

Applications

• Memory mapping in embedded systems
• I/O expansion for microcontrollers
• Bidirectional level shifting between 3.3V and 5V subsystems

Procurement Notes

Verify the manufacturer origin, as onsemi acquired Fairchild Semiconductor's logic business. Confirm the package type is TSSOP-48 and check for RoHS compliance status. Ensure the DIR and OE pin configurations match your schematic requirements before ordering.

Selection Notes

Select this component when an 8-bit wide bidirectional interface is required with mixed voltage levels. It is suitable for applications needing high-speed data transfer with low power consumption. Consider the TSSOP-48 footprint constraints and thermal performance during PCB layout.

Part Context

This part belongs to the 74LCX series, designed for low-voltage CMOS applications. It replaces older 74HC or 74HCT counterparts where lower voltage operation and 5V tolerance are critical. The device integrates buffer/register functionality to stabilize data on bidirectional buses.

Replacement Considerations

Direct substitutes include the 74LCX646MTC without the X suffix, or equivalent parts from other manufacturers such as NXP or TI within the same LCX family. Verify pin compatibility and electrical characteristics before substitution.