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Zener diodes unit of measurement special diodes that permit current not exclusively at intervals the forward direction variety of a standard diode, but in addition at intervals the reverse direction if the voltage is larger than the breakdown voltage. This voltage is known thanks to the “Zener Breakdown Voltage”.Zener breakdown is observed in extraordinarily doped PN junctions, with a tunneling mechanism and happens for voltages of regarding 5 V or less. In extraordinarily doped p-n junctions, natural phenomenon and valence bands on the alternative facet of the junction, become so shut throughout the reverse-bias that the electrons on the p-side can tunnel.

Junction Breakdown or Reverse Breakdown:

  • An applied reverse bias (voltage) will finish associate exceedingly|in a very} very little current to flow through the device.
  • At a particularly high voltage worth, that’s named as breakdown voltage VB, huge currents begin to flow. If there’s no current limiting device that’s connected asynchronous with the diode, the diode is destroyed

I-V Characteristics curve

A Zener diode could {also be|is also} a semiconductor PN junction that’s designed for operation in associate passing reverse-breakdown region.

When a diode reaches a reverse breakdown, its voltage remains nearly constant though this changes drastically, and this is {often|this will be} typically key to the Zener diode operation.

Zener Breakdown Characteristic

As the reverse voltage (VR) can increase, the reverse current(IR) remains terribly little up to the knee of the curve.

Reverse current is in addition called Zener current(Iz).

At knee purpose the breakdown impact begins, the inner Zener resistance (ZZ) begins to decrease.

The reverse current increase quickly.

The Zener breakdown (VZ) voltage remains nearly constant.

Zener Regulation

The ability to remain the reverse voltage constant across its terminal is that the key feature of the Zener diode.

It maintains constant voltage over a variety of reverse current values.

A minimum reverse current Izk ought to be maintained thus on keep diode in regulation mode. Voltage decreases drastically if this is reduced below the knee of the curve.

Above Izm, soap current, the Zener would possibly get broken permanently.