a. Design the network of Fig. to maintain VL at 12 V for a load variation (IL) from 0 mA t...

Calculate the load resistance \(R_{L}\).

$$ R_{L}=\frac{V_{Z}}{I_{L}} $$

Here,

Zener voltage \(V_{Z}\) is \(12 \mathrm{~V}\)

Load current \(I_{L}\) is \(200 \mathrm{~mA}\)

Substitute \(12 \mathrm{~V}\) for \(V_{Z}\) and \(200 \mathrm{~mA}\) for \(I_{L}\) to obtain \(R_{L}\).

$$ \begin{aligned} R_{L} &=\frac{V_{Z}}{I_{L}} \\ &=\frac{12 \mathrm{~V}}{200 \mathrm{~mA}} \\ &=60 \Omega \end{aligned} $$

Calculate the source resistance \(R_{s}\).

\(V_{L}=\frac{R_{L} V_{i}}{R_{L}+R_{S}}\)

Here,

Input voltage \(V_{i}\) is \(16 \mathrm{~V}\)

Load voltage \(V_{L}\) is \(12 \mathrm{~V}\)

Substitute \(16 \mathrm{~V}\) for \(V_{i}, 60 \Omega\) for \(R_{L}\) and \(12 \mathrm{~V}\) for \(V_{L}\) to obtain \(R_{s}\).

\(12=\frac{(60)(16)}{60+R_{s}}\)

\(720+12 R_{S}=960\)

\(12 R_{S}=240\)

\(R_{S}=20 \Omega\)

Therefore, the value of the source resistance \(R_{S}\) is \(20 \Omega\).

(b)

Calculate the maximum Zener diode power \(P_{z_{\max }}\).

\(\begin{aligned} P_{Z_{\operatorname{man}}} &=V_{Z} I_{Z_{\max }} \\ &=(12 \mathrm{~V})(200 \mathrm{~mA}) \\ &=2.4 \mathrm{~W} \end{aligned}\)

Therefore, the maximum Zener diode power \(P_{Z_{\text {eax }}}\) is \(2.4 \mathrm{~W}\).