Difference between Zener diode and normal Rectifier diode

All diodes are passive devices that allow the flow of current in one direction only while blocking the current flow completely in the opposite direction. But since there are so many types of a diode, how to differentiate between them and most importantly which one to use according to its requirement in our circuit? So by the end of this post, you will be familiar with the “Difference between a Zener diode and a normal Rectifier diode”

Before jumping to the basics of a rectifier or Schottky diode, let’s look at some of the basic characteristics of diodes.

Basic Characteristics of a Diode:-

Various characterstics of a diode
Various characteristics of a diode

** Image Source: Electronicstutorial

Diode’s Property Definition
Vf It indicates the forward voltage drop when current flows from the P to N terminal of the diode.
If It is the maximum fwd current a diode can handle
VR It is the reverse break down voltage when current flows from N to P terminal.
IR The amount of current that flows when a diode is reverse biased.
tRR When a diode is switched off suddenly, the fwd current flowing through the diode takes a small amount of time to die down and this time is called Reverse Recovery Time.

 

Rectifier Diode:

  • A rectifier diode is the simplest p-n junction diode, used mostly for rectification purposes in a half-bridge and full-bridge rectifier. And that’s because of its high break down voltage, typically of the order of 200 to 1000 volts which is obvious.
  • The forward voltage drop (Vf) of a rectifier diode is between 0.7 to 0.9 volt.
Rectifier Diodes in a Full bridge rectifier circuit
Rectifier Diodes in a Full bridge rectifier circuit
  • As an example, let’s say you want to design a bridge rectifier for your ac to dc converter project. For this bridge rectifier, the diode of the 1N4 rectifier series is an optimum choice.
1N4007 diode in a Bridge Rectifier Circuit
1N4007 diode in a Bridge Rectifier Circuit

 

Read Difference between Zener and Schottky diode OR Difference between Rectifier and Schottky diode instead.

 

Zener Diode:

  • A Zener diode is made up of a PN junction but heavily doped compared to a normal diode. As a result, it can undergo breakdown without being damaged.
  • And Due to this property only, Zener is used as a voltage regulator in electronic circuits.
  • In fact, Zener diodes are never used for rectification purposes.
Zener Diode is Heavily doped
Zener Diode is Heavily doped
What is a Voltage Regulator
What is a Voltage Regulator
  • In the circuit given below, a Zener diode is used to prevent the MOSFET gate from being destroyed by clipping off the voltage.
Zener diode as a Voltage Regulator
Zener diode as a Voltage Regulator
  • The breakdown voltage of this Zener is 5.1 volts. Now if accidentally voltage at the gate of MOSFET exceeds 5v, breakdown of the diode occurs and all the current flows through the diode to ground. Thus preventing the MOSFET from getting destroyed.
  • Here’s another circuit in which two Zener diodes are connected facing each other’s p terminal. If an A.C signal is given at the input, one diode clips of voltage in positive half whereas other in negative half and thus we get voltage under the specified limit in both the half cycle of the input A.C voltage.
Zener diodes in a Circuit
Zener diodes in a Circuit

 

Application of a Zener diode:

Digital Voltmeter using Arduino
Digital Voltmeter using Arduino
  • As an example, I used a 5V Zener in the project “Digital voltmeter using Arduino“. It is connected across the capacitor(analog pin) to prevent the Arduino in case the voltage at its analog pin exceeds the 5 volts limit.

And ending with the application above, now you know all the basic differences between Zener diode and Rectifier diode.

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