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Made Easy Test Series

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1 1 vote

A 3 to 8 decoder is shown below:

All output lines of decoder will be high when all the input I1, I2, I3 are;

  1. are high and G1 , G2 are low
  2. are high and G1 is high , G2 is low
  3. are high and G1 is low , G2 is high
  4. are high and G1 , G2 are high

Please someone help to understand the logic behind this question. Why we have to disable the Decoder to make all the outputs high ?

1 Answer

1 1 vote

@Rajat Agrawal007

B. are high and G1 is high , G2 is low ..

In 3 × 8 decoder, when all the input lines are high then all output lines of chip will be high because outputs are active low, So all the output lines of chip will be high, when chip will be disabled i.e, when G1 = 0, G2 = 1 ...

 

### Why we have to disable the Decoder to make all the outputs high ?

 

1. https://www.iitg.ac.in/psm/indexing_ma251/y11/LectureNoteMA251Jan31.pdf 

 

2. https://dducollegedu.ac.in/Datafiles/cms/ecourse%20content/Chapter-2.pdf

 

3. https://en.wikipedia.org/wiki/Binary_decoder

 

 

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