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Flip-Flops
Comments
Question
An invalid condition in the operation of an active-HIGH input S-R latch occurs when ________.
Options
A. HIGHs are applied simultaneously to both inputs S and R
B. LOWs are applied simultaneously to both inputs S and R
C. a LOW is applied to the S input while a HIGH is applied to the R input
D. a HIGH is applied to the S input while a LOW is applied to the R input
Correct Answer
HIGHs are applied simultaneously to both inputs S and R
Flip-Flops problems
Search Results
1. What is another name for a one-shot?
Options
A. Monostable
B. Multivibrator
C. Bistable
D. Astable
Show Answer
Scratch Pad
Discuss
Correct Answer: Monostable
2. What does the triangle on the clock input of a
J-K
flip-flop mean?
Options
A. level enabled
B. edge-triggered
Show Answer
Scratch Pad
Discuss
Correct Answer: edge-triggered
3. The output pulse width of a 555 monostable circuit with R
1
= 4.7 kΩ and C
1
= 47 µF is ________.
Options
A. 24 s
B. 24 ms
C. 243 ms
D. 243 µs
Show Answer
Scratch Pad
Discuss
Correct Answer: 243 ms
4. Propagation delay time, t
PLH
, is measured from the ________.
Options
A. triggering edge of the clock pulse to the LOW-to-HIGH transition of the output
B. triggering edge of the clock pulse to the HIGH-to-LOW transition of the output
C. preset input to the LOW-to-HIGH transition of the output
D. clear input to the HIGH-to-LOW transition of the output
Show Answer
Scratch Pad
Discuss
Correct Answer: triggering edge of the clock pulse to the LOW-to-HIGH transition of the output
5. As a general rule for stable flip-flop triggering, the clock pulse rise and fall times must be:
Options
A. very long.
B. very short.
C. at a maximum value to enable the input control signals to stabilize.
D. of no consequence as long as the levels are within the determinate range of value.
Show Answer
Scratch Pad
Discuss
Correct Answer: very short.
6. The timing network that sets the output frequency of a 555 astable circuit contains ________.
Options
A. three external resistors are used
B. two external resistors and an external capacitor are used
C. an external resistor and two external capacitors are used
D. no external resistor or capacitor is required
Show Answer
Scratch Pad
Discuss
Correct Answer: two external resistors and an external capacitor are used
7. If an active-HIGH S-R latch has a 0 on the S input and a 1 on the R input and then the R input goes to 0, the latch will be ________.
Options
A. SET
B. RESET
C. clear
D. invalid
Show Answer
Scratch Pad
Discuss
Correct Answer: RESET
8. What is the difference between the enable input of the 7475 and the clock input of the 7474?
Options
A. The 7475 is edge-triggered.
B. The 7474 is edge-triggered.
Show Answer
Scratch Pad
Discuss
Correct Answer: The 7474 is edge-triggered.
9. What is the significance of the
J
and
K
terminals on the J-K flip-flop?
Options
A. There is no known significance in their designations.
B. The
J
represents "jump," which is how the
Q
output reacts whenever the clock goes high and the
J
input is also HIGH.
C. The letters were chosen in honor of Jack Kilby, the inventory of the integrated circuit.
D. All of the other letters of the alphabet are already in use.
Show Answer
Scratch Pad
Discuss
Correct Answer: The letters were chosen in honor of Jack Kilby, the inventory of the integrated circuit.
10. If both inputs of an S-R flip-flop are low, what will happen when the clock goes HIGH?
Options
A. An invalid state will exist.
B. No change will occur in the output.
C. The output will toggle.
D. The output will reset.
Show Answer
Scratch Pad
Discuss
Correct Answer: No change will occur in the output.
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