µC or

System Logic

OE

V

GND

A1

A4

Y1

Y4

Regulated 3.3 V

µC

System Logic

LEDs

CC

SN74LVC240A

www.ti.com

SCAS293L – JANUARY 1993 – REVISED JULY 2014

10 Application and Implementation

10.1 Application Information

The SN74LVC240A device is a high drive CMOS device that can be used for a multitude of bus-interface type

applications where the data needs to be retained or latched. It can produce 24 mA of drive current at 3.3 V

making it ideal for driving multiple outputs and also good for high-speed applications up to 100 Mhz. The inputs

are 5.5 V tolerant allowing it to translate down to VCC.

10.2 Typical Application

Figure 4. Typical Application Diagram

10.2.1 Design Requirements

This device uses CMOS technology and has balanced output drive. Care should be taken to avoid bus

contention because it can drive currents that would exceed maximum limits. The high drive will also create fast

edges into light loads; therefore, routing and load conditions should be considered to prevent ringing.

10.2.2 Detailed Design Procedure

1. Recommended Input Conditions

–

Rise time and fall time specs: See (

Δt/ΔV) in the Recommended Operating Conditions table.

–

Specified high and low levels: See (VIH and VIL) in the Recommended Operating Conditions table.

–

Inputs are overvoltage tolerant allowing them to go as high as 5.5 V at any valid VCC.

2. Recommend Output Conditions

–

Load currents should not exceed 25 mA per output and 50 mA total for the part.

–

Outputs should not be pulled above VCC.

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