What is breakdown voltage?
Have you ever wondered why an insulating material suddenly loses its ability to block current and becomes a conductor? That's when breakdown voltage comes into play. Also known as dielectric strength, this is the minimum voltage level at which the insulating material can no longer maintain its ability to block current, creating dangerous discharges or leakage currents.
Although the theory may sound dry, in practice, breakdown voltage plays an important role in the design and testing of electronic components and electrical equipment to ensure safe operation.
Three common types of breakdown voltage
In fact, breakdown voltage does not have just one form but is divided into three main types: Diode Breakdown, Zener Breakdown and Avalanche Breakdown. Each type has a separate operating mechanism, directly affecting the performance and application of electronic components.
Diode breakdown voltage
A diode is a semiconductor device that acts as an electronic switch that allows current to flow in only one direction. It is made up of two layers of semiconductor material, P and N, which form a junction barrier that prevents current from flowing when reverse biased.
But what happens when the reverse voltage increases to a critical level? At a certain threshold, this barrier breaks down, causing the reverse current to surge – this phenomenon is the diode’s breakdown voltage. This is an important factor to control when designing a circuit, because if this limit is exceeded, the diode may be damaged or malfunction.
Breakdown Voltage of Zener Diode
Zener diodes are a common component in electronic circuits, especially when a stable reference voltage is required. The special feature of Zener diodes is their ability to operate in the reverse bias region, where breakdown voltage occurs due to the Zener effect.
When the reverse bias voltage increases to a certain level, the electric field in the Zener diode is strong enough to cause the valence electrons to “jump” into the conduction band, causing a phenomenon called “tunneling” – where these electrons can move freely. This process increases the reverse current, leading to an increase in the number of minority charge carriers. The minimum voltage level at which the Zener effect begins to occur is called the Zener breakdown voltage. This is an important factor for the Zener diode to be able to act as a reference voltage in an electronic circuit, helping to stabilize the voltage for other components.
Avalanche Breakdown
Another form of breakdown that occurs in a diode is the Avalanche Breakdown effect. This is due to the electric field being so strong that the minority charge carriers gain kinetic energy and collide violently with the electron holes in the diode. This collision breaks their covalent bonds, creating new charge carriers.
As a result, the number of charge carriers increases, leading to a sharp increase in reverse current, which eventually leads to the breakdown of the diode. The breakdown voltage in this case is called Avalanche Breakdown, and it usually occurs when the reverse bias voltage is too high. This is an important factor to control when designing a circuit, especially in applications that require high voltage tolerance.
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