Digital Electronics:: Logic Families and Their Characteristcs
Digital Electronics:: Logic Families and Their Characteristcs
11. What is the difference between the 54XX and 74XX series of TTL logic gates?
- 54XX is faster.
- 54XX is slower.
- 54XX has a wider power supply and expanded temperature range.
- 54XX has a narrower power supply and contracted temperature range.
12. An open collector output can ________ current, but it cannot ________.
- sink, source current
- source, sink current
- sink, source voltage
- source, sink voltage
13. Why is a decoupling capacitor needed for TTL ICs and where should it be connected?
- to block dc, connect to input pins
- to reduce noise, connect to input pins
- to reduce the effects of noise, connect between power supply and ground
14. 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.
- 2 mA
- 4 mA
- 8 mA
- 18 mA
15. Using the schematic diagram of a TTL NAND gate, determine the state of each transistor (ON or OFF) when all inputs are high.
- Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
- Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
- Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
- Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
16. If all inputs to a TTL NAND gate are low, what is the ON, OFF condition of each transistor in the circuit?
- Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
- Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
- Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
- Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
17. Which of the following summarizes the important features of emitter-coupled logic (ECL)?
- low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
- good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time
- low propagation time, high-frequency response, low power consumption, and high output voltage swings
- poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power
18. Why is a pull-up resistor needed for an open collector gate?
- to provide Vcc for the IC
- to provide ground for the IC
- to provide the HIGH voltage
- to provide the LOW voltage
19. Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
- to increase the output LOW voltage
- to decrease the output LOW voltage
- to increase the output HIGH voltage
- to decrease the output HIGH voltage
20. The word "interfacing" as applied to digital electronics usually means:
- a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate
- a circuit connected between the driver and load to condition a signal so that it is compatible with the load
- any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors
- any TTL circuit that is an input buffer stage