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 Ω and 1 kΩ, respectively. What is the range of V_{i} that will maintain the Zener diode in the ‘on’ state?

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Option 2 : 24 V to 36 V

For the zenor diode to be on minimum voltage across it should be 20V.

\({V_z} = {V_{RL}} = {V_i}\left( {\frac{{{R_L}}}{{{R_1} + {R_L}}}} \right)\)

\({V_z} = {V_i}\left( {\frac{{1000}}{{1000 + 200}}} \right) \ge 20\)

\(Vi \ge \frac{{20 \times 1200}}{{1000}}\)

Vi ≥ 24 V

Only option (B) satisfies this condition.

This objective approach solves time to calculate the upper bound on V_{i}

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