Zener Diode

Course Objectives

• Student Outcomes by Class End:

  • Describe the Zener Diode & its Characteristics

  • Discuss Zener equivalent circuits.

  • Apply Zener Diode in voltage regulation.

Zener Diode Overview

• Description and Characteristics:

  • Operates in reverse breakdown region.

  • Zener breakdown occurs at low reverse voltages.

  • Available Zener potentials range from 1.8 V to 200 V.

Zener Diode Behavior

• Breakdown Types:

  • Avalanche Breakdown

  • Zener Breakdown

• Breakdown Characteristics:

  • Parameters:

    • Vz: Zener voltage

    • VR: Voltage across the Zener

    • IZK: Zener knee current

    • IZM: Zener maximum current

Zener Equivalent Circuits

• Ideal vs Practical Model:

  • Ideal Model:

    • Figure representation of ideal characteristic curve.

  • Practical Model:

    • Adjustments in the Zener voltage and current calculations.

Zener Diode Regulation

• Function in Voltage Regulation:

  • Regulates varying DC input voltage.

  • Maintains constant output voltage (Vout) with variations in input (Vin).

Analysis of Zener Diode Circuits

1. Fixed Vi and RL:

   • Zener diode turns 'on' if V > Vz.

   • Appropriate equivalent model is used for analysis during active state.

2. Fixed Vi, Variable RL:

   • Determine the minimum load resistance (RL) for Zener 'on' state.

   • Circuit analysis involves calculating voltage (VL) across load resistor.

3. Fixed RL, Variable Vi:

   • Minimum Vi required to keep Zener 'on' must overcome specific voltage thresholds.

   • Define the maximum Vi based on maximum Zener current (IZM).

Example Problems

• Tasks Include:

  • Determining values for RL, IL, XOR potential loads

  • Evaluating range of Vi to maintain Zener functionality

  • Max wattage rating for a specific Zener diode configuration.

Additional Notes

• Consider characteristics depicted in graphical representations for practical understanding.

• Review specific calculations for resultant voltage across components based on Zener formulae.