Q.1

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

  • 1 time constant (RC)
  • 2 time constants (RC)
  • 5 time constants (RC)
  • 10 time constants (RC)
Q.2

Can the automatic RC circuit be used to set a flip-flop rather than reset the flip-flop?

  • yes
  • no
Q.3

A Schmitt trigger:

  • has two trip points
  • is a zero crossing detector
  • has positive feedback
  • has two trip points and positive feedback
Q.4

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

  • ts, th
  • tPHL, tPLH
  • tw (L), tw (H)
  • fmax
Q.5

Why does the data sheet for the 7476 only give a minimum value for the clock pulse width (both HIGH and LOW)?

  • nominal value
  • best-case condition
  • worst-case condition
Q.6

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

  • A delay gate is never needed.
  • to provide for setup times
  • to provide for hold times
  • to provide for setup times and hold times
Q.7

When the inputs to a flip-flop are changing at the same time that the active trigger edge of the input clock is making its transition, this condition is called:

  • racing
  • toggling
  • slave loading
  • pulse timing
Q.8

Is the propagation delay from the clock to the output for the 7476 the same as the delay from the set or reset to the output?

  • yes
  • no
Q.9

Why does the data sheet for the 7476 only give a minimum value for the clock pulse width (both HIGH and LOW)?

  • nominal value
  • best-case condition
  • worst-case condition
Q.10

Is the propagation delay from the clock to the output for the 7476 the same as the delay from the set or reset to the output?

  • yes
  • no
Q.11

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

  • 5 ns
  • 10 ns
  • 20 ns
  • 40 ns
Q.12

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

  • LOW-level current is smaller.
  • LOW-level current is larger.
  • HIGH-level current is larger.
  • LOW-level current is smaller and HIGH-level current is larger.
Q.13

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

  • to provide a triangle wave
  • to provide a sine wave
  • to provide a rounded pulse waveform
  • to provide a sharp pulse waveform
Q.14

An optocoupler is an integrated circuit with an LED and a zener diode encased in the same package.

  • True
  • False
Q.15

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

  • the low power dissipation of the resistor
  • it will keep a floating terminal LOW
  • the high power dissipation of the resistor
  • it will cause false triggering
Q.16

A Schmitt trigger has VT+ = 2.0 V and VT– = 1.2 V. What is the hysteresis voltage of the Schmitt trigger?

  • 0.4 volt
  • 0.6 volt
  • 0.8 volt
  • 1.2 volts
Q.17

Which of the following circuit parameters would be most likely to limit the maximum operating frequency of a flip-flop?

  • setup and hold time
  • clock pulse HIGH and LOW time
  • propagation delay time
  • clock transition time
Q.18

Look up the propagation delay from the clock to the output for theAre the HIGH-to-LOW and LOW-to-HIGH propagation delays the same?

  • yes
  • no, tPLH = 25 ns, tPHL = 40 ns
  • no, tPLH = 40 ns, tPHL = 25 ns
  • no, tPHL = 25 ns, tPLH = 40 ns
0 h : 0 m : 1 s