Question

Design a zener regulated power supply to give 9.1V DC output with maximum load current of 50 mA. Assume that the minimum Iz required for proper functioning of zener diode is 5 mA, and the unregulated DC input is 12V. Indicate the value of Rs and power ratings of zener diode and Rs.

Answer 1

Answer on Question #75508 - Physics / Electric Circuits

Design a zener regulated power supply to give 9.1V DC output with maximum load current of $50\mathrm{mA}$ . Assume that the minimum Iz required for proper functioning of zener diode is $5\mathrm{mA}$ , and the unregulated DC input is 12V. Indicate the value of Rs and power ratings of zener diode and Rs.

Solution.

$I = \frac{U}{R}; R = \frac{U}{I}; U_{Rs} = 12V - 9.1V = 2.9V; R_s = \frac{U_{Rs}}{I} = \frac{2.9V}{0.05A} = 58\, \text{Ohm}$

$$P _ {R s} = I ^ {2} * R _ {R s} = 0. 0 5 ^ {2} * 5 8 = 0. 1 4 5 W$$ $$P _ {V d 1} = U * I = 9. 1 V * 0. 0 5 A = 0. 4 5 5 W$$

Answer. $R_{s} = 58$ Ohm, $P_{Rs} = 0.145W$ , $P_{Vd1} = 0.455W$