Determine range of V for obtaining a regulated voltage demonstrated in Figure.
For the data 0 ≤ IL ≤ 4 mA
2 ≤ IZ ≤ 8 mA
Ans:
Determination of range of V for given circuit diagram demonstrated in figure: In figure, voltage across the series or current limiting resistor equals difference between zener voltage and source voltage. Hence, current through the series resistor RS is given by
Zener diode and load resistor are in parallel. So, sum of their currents has to equal the total current, which is same as the current through series resistor. i.e.
IS= IZ+ IL
From given data the load current is in between 0 mA (ILMIN) and 4 mA (ILMAX) and Zener current is in between 2 mA (IZMIN) and 8 mA (IZMAX).
(i) Minimum value of Source Current is given by
Hence, minimum value of source voltage is given by
VS (MIN) = 50 + 10 = 60 V
(ii) Maximum value of source current is given by
Thus, maximum value of source voltage is given by VSMAX= 50 + 60 = 110 V
Value of source voltage is 50 ≤VS ≤110 V.