250+ TOP MCQs on ADC, DAC Interfacing and Answers

8051 Micro-controller Multiple Choice Questions on “ADC, DAC Interfacing”.

1. Why two pins for ground are available in ADC0804?
a) for controlling the ADCON0 and ADCON1 register of the controller
b) for controlling the analog and the digital pins of the controller
c) for both parts of the chip respectively
d) for isolate analog and digital signal

Answer: d
Clarification: Two grounds are available in ADC0804 to isolate analog signal from digital signal. This isolation provides accuracy in digital output.

2. What is the function of the WR pin?
a) its active high input used to inform ADC0804 to the end of conversion
b) its active low input used to inform ADC0804 to the end of conversion
c) its active low input used to inform ADC0804 to the start of conversion
d) its active high input used to inform ADC0804 to the start of conversion

Answer: c
Clarification: WR is active low input used to inform the ADC0804 to start the conversion process.

3. State which of the following statements are false?
a) CLK IN pin used for External Clock Input or Internal Clock with external RC element
b) INTR pin tells about the end of the conversion
c) ADC0804 IC is an 8 bit parallel ADC in the family of the ADC0800 series
d) None of the mentioned

Answer: d
Clarification: CLK IN pin is used to tell about the conversion time, INTR pin tells about the end of the conversion and ADC0804 has a resolution of 8 bits only so all three statements are true.

4. While programming the ADC0808/0809 IC what steps are followed?
a) select the analog channel, start the conversion, monitor the conversion, display the digital results
b) select the analog channel, activate the ALE signal (L to H pulse), start the conversion, monitor the conversion, read the digital results
c) select the analog channel, activate the ALE signal (H to L pulse), start the conversion, monitor the conversion, read the digital results
d) select the channel, start the conversion, end the conversion

Answer: b
Clarification: While programming the ADC0808/0809 IC firstly we need to select the channel from the A, B, C pins. Then we need to activate the ALE signal, this is needed to latch the address. Then we start the conversion from the WR pin. After monitoring the INTR pin we get to know about the end of the conversion. Then we activate the OE enable to read out data out of the ADC chip.

5. In ADC0808/0809 IC which pin is used to select Step Size?
a) Vref
b) Vin
c) Vref/2 & Vin
d) None of the mentioned

Answer: a
Clarification: Step Size is calculated by formula Vref/(2ⁿ). As ADC0808/0809 8-bit ADC value of n=8. Therefore formula becomes Vref/(2⁸) = Vref/256. If Vref = 5V then Step Size will be 5/256 i.e. 19.53mV.

6. What is the difference between ADC0804 and MAX1112?
a) ADC0804 has 8 bits and MAX1112 has 1 bit for data output
b) ADC0804 is used for adc and dac conversions whereas MAX1112 is used for serial data transmissions
c) ADC0804 has 32 bits and MAX1112 has 3 bit for data output
d) None of the mentioned

Answer: a
Clarification: ADC0804 is used for parallel ADC and MAX1112 is used for serial ADC.

7. Which of the following statements are true about DAC0808?
a) parallel digital data to analog data conversion
b) it has current as an output
c) all of the mentioned
d) none of the mentioned

Answer: a
Clarification: DAC0804 is used for parallel data to analog data conversion.

8. 8 input DAC has ________
a) 8 discrete voltage levels
b) 64 discrete voltage levels
c) 124 discrete voltage levels
d) 256 discrete voltage levels

Answer: d
Clarification: For n input DAC has 2^n discrete voltage levels.

9. INTR, WR signal is an input/output signal pin?
a) both are output
b) both are input
c) one is input and the other is output
d) none of the mentioned

Answer: c
Clarification: INTR pin tells about the end of the conversion (output) and WR pin tells us to start the conversion (input).

10. What is the function of the SCLK pin in MAX1112?
a) It is used to bring data in
b) It is used to bring data out and send in the control byte, one at a time
c) It is used to get output clock
d) It is used to get serial output

Answer: b
Clarification: SCLK is used to bring data out and send in the control byte.