The Zener diode in the circuit has a Zener voltage Vz of 15 V and a power rating of 0.5 Watt. If the input voltage is 40 V. What is the minimum value of Rs that prevents the Zener diode from being destroyed?

The Zener diode in the circuit has a Zener voltage Vz of 15 V and a power rating of 0.5 Watt. If the input voltage is 40 V. What is the minimum value of Rs that prevents the Zener diode from being destroyed? The Zener diode in the circuit has a Zener voltage Vz of 15 V and a power rating of 0.5 Watt. If the input voltage is 40 V.

Right Answer is:

750 Ω

SOLUTION

Given

VZ = 15 V

Vin = 40 V

PZ = 0.5 W = Vz . Iz

Iz = 0.5/15 = 1/30 A

The minimum value of RS that prevents Zener diode from being destroyed

Iz = (Vin − Vz)/Rs

1/30 = (40 − 15)/Rs

Rs = 750 Ω

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