Digital Design

MCQsQuestion.com has 20 Question/Answers about Topic Digital Design

The output of a standard TTL NAND gate is used to pull an LED indicator LOW. The LED is in series with a 470- resistor. What is the current in the circuit when the LED is on?

The output of a standard TTL NAND gate is used to pull an LED indicator LOW. The LED is in series with a 470- resistor. What is the current in the circuit when the LED is on?
  • A. 7.02 mA
  • B. 8.51 mA
  • C. 10.63 mA
  • D. 5.32 mA
  • Correct Answer: Option A

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

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.
  • Correct Answer: Option B

Why is the Schmitt trigger needed in the 60-Hz TTL-level clock pulse generator?

Why is the Schmitt trigger needed in the 60-Hz TTL-level clock pulse generator?
  • A. to provide a triangle wave
  • B. to provide a sine wave
  • C. to provide a rounded pulse waveform
  • D. to provide a sharp pulse waveform
  • Correct Answer: Option D

What would be the output voltage of a 7814 voltage regulator?

What would be the output voltage of a 7814 voltage regulator?
  • A. –14 V dc
  • B. +14 V dc
  • C. –8 V dc
  • D. +8 V dc
  • Correct Answer: Option B

A 0.01-F capacitor is recommended by TTL manufacturers for ________ the power supply.

A 0.01-F capacitor is recommended by TTL manufacturers for ________ the power supply.
  • A. decoupling
  • B. filtering
  • C. rectifying
  • D. grounding
  • Correct Answer: Option A

The main concern when using a pull-down resistor is:

The main concern when using a pull-down resistor is:
  • 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
  • Correct Answer: Option C

The purpose of a pull-up resistor is to keep a terminal at a ________ level when it would normally be at a ________ level.

The purpose of a pull-up resistor is to keep a terminal at a ________ level when it would normally be at a ________ level.
  • A. LOW, float
  • B. HIGH, float
  • C. clock, float
  • D. pulsed, float
  • Correct Answer: Option B

One example for the use of a Schmitt trigger is as a(n):

One example for the use of a Schmitt trigger is as a(n):
  • A. switch debouncer
  • B. racer
  • C. astable oscillator
  • D. transition pulse generator
  • Correct Answer: Option A

A Schmitt trigger has VT+

A Schmitt trigger has VT+
  • A. 0.4 volt
  • B. 0.6 volt
  • C. 0.8 volt
  • D. 1.2 volts
  • Correct Answer: Option C

A Schmitt trigger:

A Schmitt trigger:
  • A. has two trip points
  • B. is a zero crossing detector
  • C. has positive feedback
  • D. has two trip points and positive feedback
  • Correct Answer: Option D

The ________ circuit overcomes the problem of switching caused by jitter on the inputs.

The ________ circuit overcomes the problem of switching caused by jitter on the inputs.
  • A. astable multivibrator
  • B. monostable multivibrator
  • C. bistable multivibrator
  • D. Schmitt trigger
  • Correct Answer: Option D

A settable flip-flop’s normal starting state when power is first applied to a circuit is always the ________ state.

A settable flip-flop’s normal starting state when power is first applied to a circuit is always the ________ state.
  • A. reset
  • B. set
  • C. toggle
  • D. dual
  • Correct Answer: Option B

In the automatic reset circuit for a flip-flop, how long does it take the capacitor to completely charge?

In the automatic reset circuit for a flip-flop, how long does it take the capacitor to completely charge?
  • A. 1 time constant (RC)
  • B. 2 time constants (RC)
  • C. 5 time constants (RC)
  • D. 10 time constants (RC)
  • Correct Answer: Option C

How much setup time (ts

How much setup time (ts
  • A. 5 ns
  • B. 10 ns
  • C. 20 ns
  • D. 40 ns
  • Correct Answer: Option C

Why would a delay gate be needed for a digital circuit?

Why would a delay gate be needed for a digital circuit?
  • A. A delay gate is never needed.
  • B. to provide for setup times
  • C. to provide for hold times
  • D. to provide for setup times and hold times
  • Correct Answer: Option D
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