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Basics of Zener diode

The Zener diode is a special purpose diode which is used as a voltage regulator in electronic circuits.
In this post, you'll learn:
  1. How it looks and its symbol
  2. How Zener diode works
  3. How you can use Zener diode in your projects
  4. Basic terms related to Zener diode

How it looks and its Symbol

The image below displays a physical Zener on the left side. Its symbol is similar to the normal diode with the difference being a Z at its cathode (-ve). The cathode of the device is marked by a black ring.
Basics of zener diode

How it works

The ordinary diode operates in forward bias ( a condition when positive terminal of battery joins with the positive terminal of the diode), whereas a Zener always operates in reverse breakdown region.

In reverse bias it provides the rated voltage at the output. For example, a diode rated at 10 V will always provide 10 V at the output as far as it is operated at the rated voltages.

In the image below an input of 20 V is provided to the diode rated at 10 V which provides an output of 10 V at the terminal. (This is just for illustration don't use it without a resistor.) 

How you can use it

You can use it to achieve a constant voltage for your boards, electronic components and as a voltage regulator for your components. Just add a resistor and you are ready to go:

Basic terms

IZmin: The minimum operating current required by for proper regulation. This current is known as the knee current. On data, sheet is labeled as IZK
IZmax: The maximum operating current. On data sheet, it is mentioned with IZM

IZtest: The optimal value of current. This is the value for which the ratings are mentioned.

The minimum operating current is mentioned on the data sheet, whereas the maximum current is calculated from the formula: IZmax = PDmax/VZ

Zener breakdown voltage: The term relates to all components which have the operating value of 0-5 V.

Avalanche breakdown voltage: It relates to the zeners who have the reverse operating voltage between 5-250 V.

So that was all about the basics of Zener diode.

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