The working principle of a Zener diode and how to make a Zener diode regulator?

The working principle of a Zener diode and how to make a Zener diode regulator?

What is a Zener diode?

Zener diode is a diode commonly used in voltage regulators and waveform shaping.

Ordinary diodes only allow current to flow through the circuit when forward biased (current flows from the anode to the cathode), while Zener diodes also operate when reverse biased (current flows in the opposite direction).

When using a standard diode, if it is placed in reverse, there will be no current flowing.

At least, it looks like this. But in reality, if you apply enough voltage in reverse, the current will start to flow.

This voltage is called the breakdown voltage of the diode.

For example, the breakdown voltage of rectifier diode 1N4001 is 50V.

Zener diodes are essentially the same as standard PN junction diodes. However, it is specifically designed for reverse bias and has a low and specified reverse breakdown voltage.

So, why is this so interesting?

Because you are not limited to a standard forward voltage of 0.7V. You can design the breakdown voltage to be, for example, 3.3V or 12V - or many other voltages. Manufacturers refer to it as Zener voltage (Vz).

This means that the Zener diode can act as a voltage regulator, as it maintains the breakdown voltage of each terminal at an almost constant value.

How to make a Zener diode regulator

It is easy to make a voltage regulator using a Ziner: just add a resistor!

When a voltage is applied across the resistor and Zener diode (which must be higher than the Zener voltage), the diode begins to conduct in reverse and maintains a constant voltage drop of 3.3V across both ends.

The remaining voltage drops across the resistor. This means that the resistor acts as a current limiting resistor, so you can easily calculate the current using Ohm's law.

Resistance (RS) limits the maximum current that can flow through the circuit. If there is no load connected to the circuit, all current flows through the Zener diode, causing it to dissipate its maximum power.

A smaller resistance value of R provides you with a higher maximum current. But at the same time, you must ensure that the maximum rated power of the Zener is not exceeded. Therefore, choosing the appropriate series resistance value is very important.

Generally speaking, the breakdown voltage (VZ) of a Zener diode is quite constant, although it slightly increases with the increase of Zener current (IZ). VZ is usually set as the value of Zener current, known as IZ (minutes).

Zener diodes can maintain almost constant voltage in their breakdown region, making them suitable for voltage regulation even in the simplest voltage regulator applications.

The main function of a voltage regulator is to provide a stable output voltage to parallel loads. Even if there are ripples in the power supply voltage or changes in the load current, this is still the case. Zener diodes can maintain a constant voltage output as long as their reverse breakdown region maintains a current not lower than IZ (minutes).