Logic Families and Their Characteristcs Questions and Answers

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Showing 10 of 47 questions
Q11
What is the difference between the 54XX and 74XX series of TTL logic gates?
  • A 54XX is faster.
  • B 54XX is slower.
  • C 54XX has a wider power supply and expanded temperature range.
  • D 54XX has a narrower power supply and contracted temperature range.
Answer: Option C
Q12
An open collector output can ________ current, but it cannot ________.
  • A sink, source current
  • B source, sink current
  • C sink, source voltage
  • D source, sink voltage
Answer: Option A
Q13
Why is a decoupling capacitor needed for TTL ICs and where should it be connected?
  • A to block dc, connect to input pins
  • B to reduce noise, connect to input pins
  • C to reduce the effects of noise, connect between power supply and ground
Answer: Option C
Q14
Using the above specifications, determine the amount of current in the output of a logic gate if the output of the gate is a logic LOW and connected to 4 inputs.
  • A 2 mA
  • B 4 mA
  • C 8 mA
  • D 18 mA
Answer: Option C
Q15
Using the schematic diagram of a TTL NAND gate, determine the state of each transistor (ON or OFF) when all inputs are high.
  • A Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
  • B Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
  • C Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
  • D Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
Answer: Option D
Q16
If all inputs to a TTL NAND gate are low, what is the ON, OFF condition of each transistor in the circuit?
  • A Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
  • B Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
  • C Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
  • D Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
Answer: Option A
Q17
Which of the following summarizes the important features of emitter-coupled logic (ECL)?
  • A low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
  • B good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time
  • C low propagation time, high-frequency response, low power consumption, and high output voltage swings
  • D poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power
Answer: Option A
Q18
Why is a pull-up resistor needed for an open collector gate?
  • A to provide Vcc for the IC
  • B to provide ground for the IC
  • C to provide the HIGH voltage
  • D to provide the LOW voltage
Answer: Option C
Q19
Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
  • A to increase the output LOW voltage
  • B to decrease the output LOW voltage
  • C to increase the output HIGH voltage
  • D to decrease the output HIGH voltage
Answer: Option C
Q20
The word "interfacing" as applied to digital electronics usually means:
  • A a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate
  • B a circuit connected between the driver and load to condition a signal so that it is compatible with the load
  • C any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors
  • D any TTL circuit that is an input buffer stage
Answer: Option B

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