Zener Diode Calculator

A Zener diode calculator is a tool that helps determine the appropriate Zener diode for a given application based on various parameters.

It simplifies the process of selecting the correct Zener diode from a wide range of available options. The calculator takes into account factors such as the desired zener voltage, power dissipation, and other relevant specifications.

Zener Diode Calculator

Here are some sample calculations using the Zener diode calculator formulas:

Example 1: Calculating Zener Current


  • Desired Zener voltage (V_z) = 9.1 V
  • Zener resistance (R_z) = 100 Ω

To calculate the Zener current (I_z):

I_z = V_z / R_z
    = 9.1 V / 100 Ω
    = 0.091 A
    = 91 mA

Therefore, for a Zener diode with a Zener voltage of 9.1 V and a Zener resistance of 100 Ω, the Zener current would be 91 mA.

Example 2: Calculating Maximum Power Dissipation and Selecting a Suitable Zener Diode


  • Desired Zener voltage (V_z) = 24 V
  • Maximum Zener current (I_z) = 150 mA = 0.15 A

Step 1: Calculate the maximum power dissipation (P_d):

P_d = I_z * V_z
     = 0.15 A * 24 V
     = 3.6 W

Step 2: Determine a suitable Zener diode code based on the Zener voltage and power dissipation requirements.

Referring to the Zener diode code list, a suitable option could be the BZX55 series, which has a Zener voltage range of 2.4 V to 75 V and is typically rated for power dissipation up to 5 W.

Example 3: Calculating Zener Resistance for a Given Tolerance

Suppose you need to select a Zener diode with the following requirements:

  • Desired Zener voltage (V_z) = 5.6 V ± 5% (tolerance)
  • Zener current (I_z) = 75 mA = 0.075 A

Step 1: Calculate the Zener resistance (R_z) for the nominal Zener voltage:

R_z = V_z / I_z
    = 5.6 V / 0.075 A
    = 74.67 Ω

Step 2: Calculate the Zener resistance range based on the tolerance:

  • Minimum Zener voltage = 5.6 V – (5.6 V * 0.05) = 5.32 V
  • Maximum Zener voltage = 5.6 V + (5.6 V * 0.05) = 5.88 V
  • Minimum Zener resistance = 5.32 V / 0.075 A = 70.93 Ω
  • Maximum Zener resistance = 5.88 V / 0.075 A = 78.4 Ω

Therefore, for a Zener diode with a nominal Zener voltage of 5.6 V ± 5% tolerance and a Zener current of 75 mA, the Zener resistance should be within the range of 70.93 Ω to 78.4 Ω.

Referring to the Zener diode code list, a suitable option could be the BZX79 series, which has a Zener voltage range of 5.6 V to 62 V and is typically available with various tolerance options.

These examples demonstrate how the Zener diode calculator formulas can be used to determine different parameters, such as Zener current, power dissipation, and Zener resistance, and how these calculations can aid in selecting an appropriate Zener diode for a given application and its requirements.

How to use Zener Diode Calculator?

Using a Zener diode calculator is typically straightforward. Here are the general steps:

  1. Input Parameters: Enter the required parameters, such as the desired zener voltage, maximum current, or power dissipation requirements.
  2. Select Criteria: Some calculators may allow you to specify additional criteria, such as the diode package type or tolerance range.
  3. Calculate: Once you have provided the necessary inputs, the calculator will process the information and provide a list of suitable Zener diode options.
  4. Review Results: Analyze the suggested Zener diode options and choose the one that best fits your application requirements.

Zener Diode Calculator Formula

The Zener diode calculator typically uses the following formulas to determine the appropriate Zener diode:

  1. Zener Voltage (V_z): This is the desired reverse breakdown voltage of the Zener diode, which is a specified input parameter.
  2. Maximum Power Dissipation (P_d): The formula for calculating the maximum power dissipation is: P_d = I_z * V_z where I_z is the Zener current, which is also an input parameter or derived from other specifications.
  3. Zener Resistance (R_z): The Zener resistance is calculated using the formula: R_z = V_z / I_z This value is used to determine the appropriate Zener diode based on its specified Zener impedance or resistance.

These formulas, along with other relevant specifications and constraints, are used by the calculator to suggest suitable Zener diode options.

How Does Zener Diode Work?

A Zener diode is a type of semiconductor diode that is designed to operate in reverse breakdown mode. It allows current to flow in the reverse direction when the applied voltage exceeds a specific value, known as the Zener voltage or breakdown voltage.

The Zener diode’s unique behavior is achieved through a carefully controlled doping process during its manufacturing. This process creates a heavily doped p-n junction, which allows for a controlled and predictable reverse breakdown voltage.

When a reverse voltage is applied across the Zener diode that exceeds the Zener voltage, a phenomenon called Zener breakdown occurs. This breakdown creates a constant voltage drop across the diode, regardless of the current flowing through it (within certain limits).

The Zener diode’s ability to maintain a constant voltage drop makes it useful for various applications, such as:

  • Voltage regulation: Zener diodes are commonly used in voltage regulator circuits to provide a stable reference voltage.
  • Overvoltage protection: They can protect sensitive electronic components from voltage spikes or transients by clamping the voltage to a safe level.
  • Biasing circuits: Zener diodes can provide a stable bias voltage for transistors or other semiconductor devices.

Zener Diode Code List

Here is a list of common Zener diode codes and their corresponding Zener voltage ranges:

CodeZener Voltage Range (V)
BZX552.4 – 75
BZX795.6 – 62
BZX842.7 – 47
BZX852.4 – 100
BZY936.8 – 100
LN47282.4 – 47
MMBZ52383.3 – 51
MMBZ52562.4 – 62
MMBZ52595.1 – 100
MMSZ52323.3 – 43
MMSZ52362.4 – 47
MMSZ52415.1 – 75

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