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What is a Zener Diode? , Zener Diode what hota hai?

Hello friends In this article we will know what is Zener Diode? How is its working system? And we will also know what is Zener Diode Stabilizer? And learn about many facts related to it.

Zener Diode | Zener Diode

A properly doped crystal diode having a fast breakdown voltage is called a Zener diode. A Zener Diode has reverse (V) for its operation.R/IR) attribute is used. Hence, it is always connected in reverse in the circuit ie. It is always reverse biased.


Zener Diode

Let us look at the opposite characteristics of a zener diode (see Fig. 33.9). As we increase the reverse voltage from 0 V, a very small reverse Current IR (a few µA) which essentially remains constant until the breakdown voltage is reached. Once the breakdown voltage (=Vz zener voltage) is reached, the zener diode conducts heavily current.

Fig. 33.10 shows the symbol of Zener diode. It can be seen that it is the same as an ordinary diode except that the bar is turned into a z-shape.


Following points may be noted about Zener Diode:-

  1. A zener diode is like an ordinary diode except that it is properly doped so that there is a rapid breakdown voltage.
  2. Zener diode is always reverse connected ie. It is always reverse biased.
  3. The Zener diode has a fast breakdown voltage, which is called the Zener voltage V.
  4. When forward biased, it has the same characteristics as an ordinary diode.
  5. The zener diode does not light up simply because it has entered the breakdown region. As long as the external circuit connected to the diode limits the diode current to less than the burn out value, the diode will not burn out. In fact, by reducing the reverse voltage to the Zener voltage (Vz), the Zener can be brought out of its breakdown level and restored to the pre-breakdown state.

Zener Diode Voltage Stabilizer | Zener Diode Voltage Stabilizer

Zener diode as a voltage stabilizer whose voltage can vary over a sufficient range. The circuit arrangement is shown in Fig. 33.11 (1). A zener diode of zener voltage Vz is reverse connected across load R, across which continuous output is desired.

Diagram for zener diode voltage stabilizer

resistance R absorbs fluctuations in the output voltage to maintain a constant voltage across the load. It may be noted that a constant voltage V across the zener loadZ (= E0) until the input voltage falls below Vz.

When the circuit is designed properly, the load voltage E, essentially remains constant (equal to V), even though the input voltage VZ and the load resistance R, can vary over a wide range.



  • Suppose the input voltage increases. Since the zener is in the breakdown region, the zener diode battery is equal to Vz, as shown in Fig. 33.11(i). It is clear that the output voltage VZ (= E0 ) remains constant. The excess voltage is dropped across the series resistance R. This will increase the value of the total current I. The zener will conduct an increase in current I while the load current remains constant. Therefore, the output voltage Vz remains constant irrespective of the change in the input voltage Ei.
  • Now suppose the input voltage is constant but the load resistance RL becomes less. This will increase the load current. The additional current cannot come from the source because the drop in R (and hence the source current I) will not change as the zener is within its regulatory range. The additional load current will come from a decrease in the zener current Iz, as a result, the output voltage remains at a constant value (= E = V).
  • Voltage drop across R V = Ei – E0and I = IZ + IL Applying Ohm’s law, R = V/I or (E)i – E0)/(IZ + IL,

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