Unused Input

Input

Output

Input

Unused Input

Output

SN74AHC1GU04

www.ti.com

SCLS343R – APRIL 1996 – REVISED DECEMBER 2014

12 Layout

12.1 Layout Guidelines

When using multiple bit logic devices, inputs should not float. In many cases, functions or parts of functions of

digital logic devices are unused. Some examples are when only two inputs of a triple-input AND gate are used,

or when only 3 of the 4-buffer gates are used. Such input pins should not be left unconnected because the

undefined voltages at the outside connections result in undefined operational states.

Specified inFigure 7 are rules that must be observed under all circumstances. All unused inputs of digital logic

devices must be connected to a high or low bias to prevent them from floating. The logic level that should be

applied to any particular unused input depends on the function of the device. Generally they will be tied to GND

transceiver. If the transceiver has an output enable pin, it will disable the outputs section of the part when

asserted. This will not disable the input section of the I/Os so they also cannot float when disabled.

12.2 Layout Example

Figure 7. Layout Diagram

13 Device and Documentation Support

13.1 Trademarks

All trademarks are the property of their respective owners.

13.2 Electrostatic Discharge Caution

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

13.3 Glossary

SLYZ022 — TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

14 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

Copyright © 1996–2014, Texas Instruments Incorporated

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11

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