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- Question
Define a race condition for a flip-flop.
Options- 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.
- Correct Answer
- The inputs to a trigger device are changing at the same time as the active trigger edge.
- 1. Why should a LED be pulled LOW from a logic gate rather than pulled HIGH?
Options- 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. Discuss
- 2. A Schmitt trigger has VT+ = 2.0 V and VT? = 1.2 V. What is the hysteresis voltage of the Schmitt trigger?
Options- A. 0.4 volt
- B. 0.6 volt
- C. 0.8 volt
- D. 1.2 volts Discuss
- 3. A Schmitt trigger:
Options- A. has two trip points
- B. is a zero crossing detector
- C. has positive feedback
- D. has two trip points and positive feedback Discuss
- 4. Why does the data sheet for the 7476 only give a minimum value for the clock pulse width (both HIGH and LOW)?
Options- A. nominal value
- B. best-case condition
- C. worst-case condition Discuss
- 5. The purpose of a pull-up resistor is to keep a terminal at a ________ level when it would normally be at a ________ level.
Options- A. LOW, float
- B. HIGH, float
- C. clock, float
- D. pulsed, float Discuss
- 6. Which of the following flip-flop timing parameters indicates the time it takes a Q output to respond to a Cp input?
Options- A. ts, th
- B. tPHL, tPLH
- C. tw (L), tw (H)
- D. fmax Discuss
- 7. The main concern when using a pull-down resistor is:
Options- A. the low power dissipation of the resistor
- B. it will keep a floating terminal LOW
- C. the high power dissipation of the resistor
- D. it will cause false triggering Discuss
- 8. What is the major advantage of the J-K flip-flop over the S-R flip-flop?
Options- A. The J-K flip-flop is much faster.
- B. The J-K flip-flop does not have propagation delay problems.
- C. The J-K flip-flop has a toggle state.
- D. The J-K flip-flop has two outputs. Discuss
- 9. The ________ circuit overcomes the problem of switching caused by jitter on the inputs.
Options- A. astable multivibrator
- B. monostable multivibrator
- C. bistable multivibrator
- D. Schmitt trigger Discuss
- 10. The output of a standard TTL NAND gate is used to pull an LED indicator LOW. The LED is in series with a 470-Ω resistor. What is the current in the circuit when the LED is on?
Options- A. 7.02 mA
- B. 8.51 mA
- C. 10.63 mA
- D. 5.32 mA Discuss
Digital Design problems
Search Results
Correct Answer: LOW-level current is larger.
Correct Answer: 0.8 volt
Correct Answer: has two trip points and positive feedback
Correct Answer: worst-case condition
Correct Answer: HIGH, float
Correct Answer: tPHL, tPLH
Correct Answer: the high power dissipation of the resistor
Correct Answer: The J-K flip-flop has a toggle state.
Correct Answer: Schmitt trigger
Correct Answer: 7.02 mA
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