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close this bookDigital Teaching Aid (DED Philippinen, 86 p.)
close this folderKarnaugh Mapping II - Lesson 5
close this folderLesson Plan
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View the documentIntroduction
View the documentProduct of sums method
View the documentDon't care conditions

Don't care conditions

In some digital systems, certain input conditions never occur during normal operations; therefore, the corresponding output never appears.

Þ It is indicated in the truth table by an X.

Fig. 5-5: Don't care conditions

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Don't care conditions

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Don't care conditions are like wild cards, you can let them stand for what ever you like:


Fig. 5-6: Karnaugh map and simplified equation

HO: Simplify the following Boolean function:

That has the don't care conditions:

Solution:

First we have to translate the function into a truth table:

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Now we have to convert it into a Karnaugh map and simplify it:


Figure