**What is the maximum and minimum output voltages for IC voltage regulator shown below if adjustable current and input voltage are 98.5 µA and 40 V respectively with the variable range of resistances from zero to 5 k ohm ?** **Options:** a. 30.16 V & 1.25

b. 29.66 V & 0 V

c. 27.99 V & 0 V

d. 31.49 V & 1.25V

Correct Answer: d. 31.49 V & 1.25V

**Explanation** According to the equation of output voltage for IC voltage regulator,

V

_{out} = V

_{ref} [ 1+ (R2/ R1) ] + I

_{ADJ.} R

_{2} Considering R2 at its minimum value = 0 ohm, the output voltage is evaluated by,

V

_{out (min)} = 1.25 [ 1 + (0 / 210 )] + (98.5 x10

^{-6} ) x 0

= 1.25 V

For maximum value of R2 = 5 k ohm, the output voltage is,

V

_{out (max)} = 1.25 [ 1 + (5 x 10

^{3} / 210)] + (98.5 x 10

^{-6} ) x 5 x 10

^{3} = 1.25 [ 1+ (5000 / 210) ] + (98.5 x 10

^{-6} ) x 5000

= 31 + 0.4925

= 31. 49 V