7 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

7.1 Application Information

The SNx4AHCT240 device is a low-drive CMOS device that may be used for a multitude of bus interface type

applications where output ringing is a concern. The low drive and slow edge rates will minimize overshoot and

undershoot on the outputs. The input switching levels have been lowered to accommodate TTL inputs of 0.8-V

VIL and 2-V VIH. This feature makes the SNx4AHCT240 device ideal for translating up from 3.3 V to 5 V. Figure

7-1 shows this type of translation.

7.2 Typical Application

C or System

Logic

SNx4AHCT240

A1

A4

OE

Y1

Y2

VCC

GND

C/System

Logic/LEDs

5 V

3.3 V

Copyright © 2018, Texas Instruments Incorporated

Figure 7-1. Application Diagram

7.2.1 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.

7.2.2 Detailed Design Procedure

1. Recommended Input Conditions:

• For rise time and fall time specifications, see Δt/ΔV in the Section 5.3 table.

• For specified high and low levels, see VIH and VIL in the Section 5.3 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 75 mA total for the part.

• Outputs should not be pulled above VCC.

SN54AHCT240, SN74AHCT240

SCLS252P – OCTOBER 1995 – REVISED JANUARY 2025

www.ti.com

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