74LCX646WM

Overview

The onsemi 74LCX646WM is a low voltage octal transceiver and register featuring 5V tolerant inputs and outputs. It operates within a VCC range of 2.3V to 3.6V, utilizing advanced CMOS technology for high-speed operation with low power dissipation. The device supports multiplexed transmission of data directly from the input bus or internal storage registers. Key electrical specifications include a maximum propagation delay of 7.0 ns at 3.3V, a maximum quiescent supply current of 10 µA, and an output drive capability of ±24 mA at 3.0V. It provides live insertion/withdrawal support and implements patented noise reduction circuitry.

Feature Summary

• Features 5V tolerant inputs and outputs for interfacing with 5V signal environments while operating at lower voltages.
• Supports live insertion and withdrawal capabilities when configured correctly during power transitions.
• Implements patented noise and EMI reduction circuitry to enhance signal integrity.
• Provides registered bus transceiver functionality with D-type flip-flops and control circuitry.

Applications

• Multiplexed transmission of data between buses in low voltage systems
• Interfacing low voltage logic circuits with 5V signal environments
• Bus management applications requiring real-time and stored mode data transfer

Procurement Notes

Verify that the specific ordering code matches the required package type, as the WM suffix denotes the SOIC-24 variant. Confirm operational voltage requirements align with the 2.3V to 3.6V specification range. Ensure OE pin configuration includes a pull-up resistor if live insertion support is required to maintain high-impedance states during power cycles. Check compliance with RoHS standards if applicable to your manufacturing process.

Selection Notes

Select this component when designing systems requiring bidirectional data transfer between 8-bit buses with optional storage. It is suitable for applications needing 5V tolerance on both inputs and outputs while powered by 3.3V or 2.5V supplies. Consider its propagation delay and drive strength for timing-critical interfaces. Evaluate the need for registered versus transparent modes based on system synchronization requirements.

Part Context

This device belongs to the LCX family of low voltage CMOS logic integrated circuits. It combines the functionality of an octal bus transceiver with dual 8-bit registers. The design allows for flexible data routing between Bus A and Bus B, controlled by direction and enable signals. It is fabricated using advanced CMOS processes to achieve performance comparable to faster logic families while maintaining low power consumption.

Replacement Considerations

Check datasheets for equivalent octal transceivers with 5V tolerance and similar voltage ranges. Verify pin compatibility and logical truth tables before substitution. Ensure replacement parts meet the same 5V I/O tolerance and low power specifications required by the original design constraints.

FAQ

How does the device handle data transfer between buses?

Data can be transferred in real-time (transparent mode) or stored in internal registers before being output, controlled by select inputs and clock pulses.

What is the purpose of the OE pin regarding power down?

To ensure high-impedance states during power up or down, the OE pin should be tied to VCC through a pull-up resistor to prevent unintended bus driving.

Can this device interface directly with 5V signals?

Yes, the 74LCX646WM features 5V tolerant inputs and outputs, allowing it to operate safely with 5V signal levels while powered by lower voltages like 3.3V.