MC74LCX240DTR2

Overview

The MC74LCX240DTR2 is a low-voltage CMOS octal buffer with inverting, three-state outputs. It operates from a 1.65 V to 5.5 V supply and features 5 V-tolerant inputs and outputs for TTL logic interfacing. The device provides 24 mA balanced output sink and source capability at 3 V. Propagation delay ranges from 5.9 ns to 10.3 ns depending on voltage. Quiescent supply current is near zero (10 µA). It supports live insertion and withdrawal, includes an IOFF specification for high impedance when VCC = 0 V, and offers ESD performance exceeding 2000 V via the human body model.

Feature Summary

• Features 5 V tolerant inputs and outputs allowing safe interfacing with 5 V devices while operating at lower voltages.
• Provides 24 mA balanced output drive capability at 3 V for improved switching noise performance.
• Supports live insertion and withdrawal applications through dedicated IOFF specifications ensuring high impedance during power-off states.

Applications

• Memory address driving
• TTL level bus oriented transceiver applications
• Interface capability with 5 V TTL logic

Procurement Notes

Verify that the specific part number suffix matches the required package type, as the LCX240 series is available in both TSSOP-20 and SOIC-20 WB configurations. Confirm RoHS compliance status and lead-free markings if environmental regulations apply to your assembly process. Ensure input pins are tied to appropriate logic levels rather than left floating to maintain reliability.

Selection Notes

Select this component when designing systems requiring octal buffering with mixed voltage domains between 1.65 V and 5.5 V. It is suitable for applications needing high drive strength of 24 mA and low static power consumption. Consider the propagation delay specifications relative to your system clock speeds and ensure the thermal dissipation capabilities meet your board layout requirements.

Part Context

This component belongs to the MC74LCX240 family of low-voltage CMOS buffers manufactured by onsemi. It is designed to replace older 5 V logic families in modern low-power designs. The device utilizes advanced CMOS technology to achieve high speed and low power consumption simultaneously, making it a standard solution for bus-oriented transceivers in portable and battery-operated electronics.

Replacement Considerations

Direct substitutes include the MC74LCX240DWR2G which shares identical electrical characteristics but utilizes a SOIC-20 WB package instead of the TSSOP-20 form factor. Verify pinout compatibility and physical footprint dimensions before swapping packages to ensure proper PCB trace routing and soldering alignment.

FAQ

What is the maximum input voltage allowed for the MC74LCX240?

The DC input voltage can range from 0 V to 5.5 V, allowing the inputs to be safely driven by 5 V devices even when the supply voltage is lower.

How does the device handle power-down conditions?

The IOFF specification guarantees that outputs enter a high impedance state when VCC is 0 V, preventing back-feeding currents into the power rail.