Question

A shunt regulator utilizing a zener diode with an incremental resistance of \(5\,\Omega\) is fed through an \(82\,\Omega\) resistor. If the raw supply changes by \(1.0\,\text{V}\), what is the corresponding change in the regulated output voltage?

• A. \(72.7\,\text{mV}\)
• B. \(73.7\,\text{mV}\)
• C. \(57.5\,\text{mV}\)
• D. \(75.7\,\text{mV}\)

Hint:

To find the change in regulated output voltage in a zener diode shunt regulator, use the voltage division rule: \[ \Delta V_{\text{out}} = \Delta V_{\text{in}} \times \frac{r_z}{R + r_z} \] where \( r_z \) is the zener incremental resistance, and \( R \) is the series resistance. Always ensure resistance values are correct before plugging into the formula.

Answer 1

The Correct Option is C

To solve this problem, we need to calculate the corresponding change in the regulated output voltage of a shunt regulator using a Zener diode.

1. Understanding the Shunt Regulator:

- In a shunt regulator, a Zener diode is used to maintain a stable voltage across a load. The voltage across the diode is primarily determined by the Zener breakdown voltage. The regulation of this voltage can be affected by the change in the input supply voltage, which results in a change in the current through the diode and the series resistor.

- The total change in the output voltage is determined by the combination of the Zener diode's incremental resistance and the series resistor that is in the path of the input voltage change.

2. Given Values:

- Incremental resistance of the Zener diode \( r_z = 5 \, \Omega \)

- Series resistor \( R_s = 82 \, \Omega \)

- Change in the raw supply voltage \( \Delta V_{in} = 1.0 \, \text{V} \)

3. Formula to Calculate the Change in Output Voltage:

The change in the output voltage \( \Delta V_{out} \) is given by the formula:

\[ \Delta V_{out} = \frac{r_z \Delta V_{in}}{R_s + r_z} \]

Substituting the given values:

\[ \Delta V_{out} = \frac{5 \times 1.0}{82 + 5} = \frac{5}{87} \approx 0.0575 \, \text{V} = 57.5 \, \text{mV} \]

4. Final Answer:

The corresponding change in the regulated output voltage is 57.5 mV.