sdic 2marks (q & a) [unit 2]

8/8/2019 Sdic 2marks (q & a) [Unit 2]

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UNIT-II (2 marks)

1.Define duty cycle?The ratio of high output period and low output period is given by mathematical parameter called

duty cycle. It is defined as the ratio of ON time(high output) to the total time of one cycle.

W= time for output is highT= time for one cycle

D= duty cycle=W/T%D=W/T*100

2. Explain the principle of free running multivibrator with its relations?Astable multivibrator is also called as free runnig multivibrator. The principle of generation of

square wave output is to force an op-amp to operate in the saturation region.

T1=RC ln (1+/1-)

T= 2T1If R1=R2 then

T= 2RC

F0=1/2RC

3.Why bistable is not possible in 555 timer? Explain A negative pulse to pin 2 turns the output positive A negative pulse to pin 4 turns the output negative The timer is stable in each of these sates. Its run time has become infinite

4.What is the time constant for the design of monostable multivibrator?The time constant is given by

T= RC ln (1+ VD/ V sat)/ (1-)

If R1=R2 thenT= 0.69 RC

7. State the conditions of RS flipflop with a neat table?

Qn Qn+1 R S

0 0 dont care 0

0 1 0 1

1 0 1 0

1 0 0 dont care

When S=1 & R=0, set conditionWhen S=0 & R=1, reset condition

When S=1 & R=0, set condition

8. What is the capacitor connected to pin number 5 of 555 timer? If the control voltage function is not used a 0.001 F capacitor should be connected between pin

5 & ground. This will filter any electrical noise from entering pin 5


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17. what are the two standard frequencies used for FSK flipflop?1070 hz & 1270 hz

18.Write the basic equation for D/A conversionThe basic aquatio for D/A conversion

V0 = KVFS (d1 2-1

+ d2 2-2

++ dn 2-n

)

V0 = output voltageVFS = full scale output voltage

K = scaling factor usually adjustable to unity

D1,d2.dn= n bit binaray fractional word with decimal point located at the shift.

19.What are the various D/A conversions?

Weighted resistor DAC Inverted R-2R ladder Multiplier DACs Monolithic DACs

20.What are the various A/D conversions?Direct type ADCs:

Parallel comparator A/D converter Counter type A/D converter Servo tracking A/D converter Successive approximation converter

Indirect type ADCs:

Charge balancing ADC Dual slope ADC

21. Define resolution, linearity, accuracy, stability:Resolution:

The resolution of a converter is the smallest change in voltage which may be produced at the output of theconverter

Resolution ( in volts)= VFS/2n-1

Linearity:Linearity of an A/D or D/A converter shows us how close the converter output is to its ideal transfer

characteristics

In actual DAC equal increment in the digital input should produce equal increment in the analog output

and the transfer curve should be linear and the transfer curve should be linear

The static performance of a DAC is determined by fitting a straight line through the measured outputpoints.

Accuracy:Absolute accuracy is the maximum deviation between the actual converter output and the ideal converter

output. Relative accuracy is the maximum deviation after gain and offset errors have been removed.

Stability:


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The performance of converter changes with temperature, age and power supply variations. So all the

relevant parameters such as offset, gain, linearity error and monotonicity must be specified over the fulltemperature and power supply ranges.

22. Give examples for A/D conversion ICs:

AD 7520/AD 7530 10 bit binary multiplying typeAD 7521/Ad 7531 12 bit binary multiplying type

ADC 0800/0801/0802 8 bit ADC

23. Give examples for D/A conversion ICs:

DAC 0800/0801/0802 8 bit DAC

DAC 0830/0831/0832 microprocessor compatible 8 bit DAC

DAC 1200/1201 12 bit DAC

DAC 1208/1209/1210 12 bit micrpprocessor compatible DAC

sdic 2marks (q & a) [unit 2]

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