Digital Electronics - Digital Design

Exercise :: Digital Design - General Questions

21. 

What is the difference between setup time and hold time?

A. Setup time occurs after the active clock edge, hold time occurs before the active clock edge.
B. Setup time occurs before the active clock edge, hold time occurs after the active clock edge.
C. Setup time and hold time both occur at the active clock edge.

Answer: Option B

Explanation:

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22. 

Define a race condition for a flip-flop.

A. The inputs to a trigger device are changing slightly before the active trigger edge.
B. The inputs to a trigger device are changing slightly after the active trigger edge.
C. The inputs to a trigger device are changing at the same time as the active trigger edge.

Answer: Option C

Explanation:

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23. 

Which of the following flip-flop timing parameters indicates the time it takes a Q output to respond to a Cp input?

A. ts, th
B. tPHL, tPLH
C. tw (L), tw (H)
D. fmax

Answer: Option B

Explanation:

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24. 

How much setup time (ts) is required for the 74LS76?

A. 5 ns
B. 10 ns
C. 20 ns
D. 40 ns

Answer: Option C

Explanation:

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25. 

Why should a LED be pulled LOW from a logic gate rather than pulled HIGH?

A. LOW-level current is smaller.
B. LOW-level current is larger.
C. HIGH-level current is larger.
D. LOW-level current is smaller and HIGH-level current is larger.

Answer: Option B

Explanation:

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