What determines the voltage at which a Zener diode breaks down?

What determines the voltage at which a Zener diode breaks down?

The current increases to a maximum, which is determined by the series resistor, after which it stabilizes and remains constant over a wide range of applied voltage. The breakdown is either due to the Zener breakdown effect that occurs below 5.5 V, or impact ionization that occurs above 5.5 V.

When the voltage across the diode is less than the Zener voltage?

If the voltage at the output was lower than Vz, the diode would not conduct and (if there was o other load, the voltage would rise. If the voltage at the output was higher than Vz, the diode would have low resistance and short out the output, which means that the voltage would drop (because of the resistor in series).

What is meant by Zener voltage?

The Zener voltage is the voltage at which the depletion region completely vanish. The reverse bias applies across the diode increases the intensity of electric field across the depletion region. Thus, it allows the electrons to move from the valence band of P-type material to the conduction band of N-type material.

How does Zener diode regulate the voltage?

When connected in parallel with a variable voltage source so that it is reverse biased, a Zener diode conducts when the voltage reaches the diode’s reverse breakdown voltage. From that point on, the low impedance of the diode keeps the voltage across the diode at that value.

How is the resistance of a Zener diode determined?

It is given by the product of the voltage of the diode and the current flowing through it. Zener Resistance (Rz) – It is the resistance to the Zener diode exhibits. Zener diode is used as a Shunt voltage regulator for regulating voltage across small loads. The breakdown voltage of Zener diodes will be constant for a wide range of current.

Why does the Zener voltage match the voltage at Vout?

No current will pass through the zener, and the zener is no longer conductive. With a resistive load less than 25Ω, the zener will not conduct, circuit current will increase, and Vin = Vr + Vload = 9V always. The circuit still follows Kirchoff’s voltage law.

How is a Zener diode used as a shunt voltage regulator?

Zener diode is used as a shunt voltage regulator. Zener diode is connected parallel to the load to make it reverse bias and once the Zener diode exceeds knee voltage, the voltage across the load becomes constant. Does Zener Diode exhibit a controlled breakdown?

When does avalanche breakdown occur in a Zener diode?

Avalanche breakdown occurs both in normal diode and Zener Diode at high reverse voltage. When a high value of reverse voltage is applied to the PN junction, the free electrons gain sufficient energy and accelerate at high velocities. These free electrons moving at high velocity collides other atoms and knocks off more electrons.