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GATE 2019 EC – Question 48

Analog Circuits · Diode Circuits · 2 marks · Multiple choice

In the circuit shown, the breakdown voltage and the maximum current of the Zener diode are 20 V and 60 mA, respectively. The values of $R_1$ and $R_L$ are $200\ \Omega$ and $1\ \text{k}\Omega$, respectively. What is the range of $V_i$ that will maintain the Zener diode in the 'on' state?

Diagram for GATE 2019 EC question 48
  1. 22 V to 34 V
  2. 24 V to 36 V
  3. 18 V to 24 V
  4. 20 V to 28 V

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Show answer and explanation

Correct answer: (B) 24 V to 36 V

Explanation

With the Zener on, the load current is $\frac{20}{1000}=20$ mA, and the Zener current lies between 0 and 60 mA. The current through $R_1$ is therefore between 20 mA and 80 mA, so $V_i=20+200I$ ranges from $24$ V to $36$ V.