Why do some 3 to 5 decoders only have certain inputs decoded?

  • Thread starter alvinliu
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In summary, the conversation discusses the confusion surrounding why certain inputs are being circled in a decoder and the need for specific outputs for only certain inputs. It is mentioned that there is more than one valid design for this and that the EN signal may represent an ENABLE line.
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alvinliu
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I don't know why they circle the 001 .011. 100.101. 110 .because I saw the textbook showed for 3to 4 decoder. Y0 =1 since 00. Y1 = 1 since 01. Y2 =1 since 10,Y3 = 1 since 11.

But for this problem . I am so confused.
 

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My guess is that the need was for an output only for the listed 3-bit inputs. Other states come under the "don't care" category. All that is required in the 'design' process is to find a unique combination of bits on the input (the fewer the better) to generate each of those required outputs. There is more than one valid design. e.g., an alternative which won't conflict with any of the other decoding appears to be Y1=I1.and.I0

There would be plenty of applications where they'd want every input decoded to an output, so none of these shortcuts would be possible.

The EN signal looks like an ENABLE line.
 
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1. What is a 3 to 5 decoder?

A 3 to 5 decoder is a combinational logic circuit that takes in 3 inputs and produces 5 outputs, based on the input combination. It is used to decode binary information into a specific code or signal.

2. What is the purpose of a 3 to 5 decoder?

The purpose of a 3 to 5 decoder is to expand the number of outputs available from a limited number of inputs. It can be used in various applications, such as in memory addressing, data routing, and control circuits.

3. How does a 3 to 5 decoder work?

A 3 to 5 decoder works by using a combination of logic gates, such as AND, OR, and NOT gates, to decode the input combination and produce the corresponding output. The inputs and outputs are represented in binary form, with each input combination corresponding to a unique output.

4. What are the advantages of using a 3 to 5 decoder?

One of the main advantages of using a 3 to 5 decoder is that it allows for efficient data manipulation and control with limited inputs. It also simplifies the design of complex logic circuits and reduces the number of logic gates needed, making it more cost-effective.

5. What are some common applications of a 3 to 5 decoder?

Some common applications of a 3 to 5 decoder include memory addressing in microprocessors, data routing in communication systems, and control circuits in electronic devices. It can also be used in combination with other logic circuits to perform more complex operations.

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