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"'Zener diode' and 'avalanche diode' are terms often used interchangeably, with the former much more common. Both refer to breakdown of a diode under reverse bias. Specifically, when a diode is reverse biased, very little current flows, and the diode is to a first order approximation an open circuit. As the reverse voltage is increased, though, a point is reached where there is a dramatic increase in current. Equivalently, there is a dramatic reduction in the dynamic resistance (slope of the V-I curve) that can be as low as 1- 2 W in this region.ÝThis voltage is called the reverse breakdown voltage and it is fairly independent of the reverse current flowing.ÝThis property makes it ideal as a voltage reference.Ý "Avalanche breakdown is caused by impact ionization of electron-hole pairs.ÝWhile very little current flows under reverse bias conditions, some current does flow.ÝThe electric field in the depletion region of a diode can be very high. Electron/holes that enter the depletion region undergo a tremendous acceleration.Ý As these accelerated carriers collide with the atoms they can knock electrons from their bonds, creating additional electron/hole pairs and thus additional current.ÝAs these secondary carriers are swept into the depletion region, they too are accelerated and the process repeats itself.ÝThis is akin to an avalanche where a small disturbance causes a whole mountainside of snow to come crashing down.Ý The efficiency of the avalanche effect is characterized by a so-called multiplication factor M that depends on the reverse voltage (Equation 1). Equation 1: Multiplication Factor "Here n is in the range 2 - 6, V is the applied (reverse) voltage, and Vbr is the breakdown voltage.ÝThis is an empirical relationship, as are many of the relationships used to describe both Zener and avalanche breakdown.Ý "Avalanche breakdown occurs in lightly-doped pn-junctions where the depletion region is comparatively long.ÝThe doping density controls the breakdown voltage.ÝThe temperature coefficient of the avalanche mechanism is positive.ÝThat is, as the temperature increases, so does the reverse breakdown voltage.ÝThe magnitude of the temperature coefficient also increases with increasing breakdown voltage. For example, the temperature coefficient of a 8.2 V diode is in the range 3 - 6 mV/K while the temperature coefficient of an 18 V diode is in the range ofÝ 12 - 18 mV/K. "Zener breakdown occurs in heavily doped pn-junctions.ÝThe heavy doping makes the depletion layer extremely thin. So thin, in fact,Ýcarriers canít accelerate enough to cause impact ionization.ÝWith the depletion layer so thin, however, quantum mechanical tunnelingÝ through the layer occurs causing current to flow.ÝThe temperature coefficient of the Zener mechanism is negativeóthe breakdown voltage for a particular diode decreases with increasing temperature.ÝHowever, the temperature coefficient is essentially independent of the rated breakdown voltage, and on the order ofÝ -3 mV/K. "In a 'Zener' diode either or both breakdown mechanisms may be present. At low doping levels and higher voltages the avalanche mechanism dominates while at heavy doping levels and lower voltages the Zener mechanism dominates.ÝAt a certain doping level and around 6 V for Si, both mechanism are present with temperature coefficients that just cancel. It is possible to make Zener diodes with quite small temperature coefficients.Ý "Neither Zener nor avalanche breakdown are inherently destructive in that the crystal lattice is damaged.ÝHowever, the heat generated by the large current flowing can cause damage, so either the current must be limited and/or adequate heat sinking must be supplied."

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Difference between avalanche zener and thermal breakdown?

Avalanche is when you surpass the negative bias voltage threshold and the zener breaks, thermal breakdown would be putting too much current or voltage across the zener and burning it out.


How will you differentiate the diodes whether it is Zener or avalanche when you are given two diodes of rating 6.2 v and 24V?

Oh, what a happy little question! To differentiate between Zener and avalanche diodes, you can look at their voltage ratings. A Zener diode typically has a lower voltage rating, like 6.2V, while an avalanche diode usually has a higher voltage rating, like 24V. Just remember, each diode has its own special purpose and they all bring joy to our electronic landscapes.


What is avalanche break down in scr?

Avalanche breakdown in Silicon-Controlled Rectifiers (SCRs) refers to the rapid increase in current flow through the device due to high reverse voltage. This phenomenon occurs when the reverse voltage exceeds the breakdown voltage of the SCR, causing a sudden breakdown of the junction and a rapid increase in current flow. Avalanche breakdown can damage the SCR if not properly controlled.


What is difference between avanlche break down and zener break down?

The difference between the avalanche diode (which has a reverse breakdown above about 6.2 V) and the Zener is that the channel length of the former exceeds the "mean free path" of the electrons, so there are collisions between them on the way out. The only practical difference is that the two types have temperature coefficients of opposite polarities.


Why an ordinary diode suffers avalanche break down rather than zener break down?

An ordinary diode is designed to have a high breakdown voltage, causing it to experience avalanche breakdown when the reverse bias voltage surpasses its breakdown voltage. In contrast, a Zener diode is engineered with a specific doping profile that allows it to exhibit Zener breakdown at lower voltages by enabling electron tunneling across the depletion region. This fundamental difference in design leads to the distinct breakdown behaviors in each type of diode.


When operating as a voltage regulator the breakdown in a Zener diode occurs due to which effect?

avalanche


How will you differentiate the diodes whether it is zener or an avalanche when you are given two diodes of rating 6.2V and 24V?

Silicon "zener diodes" with a zener voltage rating of 5.6V or higher operate mainly by avalanche breakdown, so both the 6.2V and 24V "zener diodes" are avalanche breakdown type (not zener breakdown type).


What is Difference between peak inverse voltage and break down voltage?

Two names for practically the same condition. Peak inverse is name whereby the maximum voltage can be sustained. Breakdown is actually the point where a reverse voltage is reached and reverse breakdown has occurred


Difference between zener diode and junction diode?

Zener diodes and ordinary junction diodes are similar, except that zener diodes have additional doping to bring their reverse breakdown voltage into a more usable value, and to allow them to not destructively avalanche when they do conduct in the reverse direction.


For a normal p-n junction diod like 1n4007 at around what forward voltage does avalanche breakdown occurs?

1KV


Difference between avalanche and zener breakdown?

A: There is no difference except for a zener its breakdown is known and predictable. Avalanche breakdown is not predictable and usually happens at hi voltage and because of it if the current is not limited it self destroy the device


Difference between diode and zener diode?

All diodes have a tiny voltage when current flows in a 'forward' direction. And a Reverse Breakdown voltage when current tries to flow in a reverse direction resulting in a high voltage. That current does not flow until voltage exceeds its breakdown number. Regular diodes have a reverse breakdown voltage that is somewhere above a number, For example a 1N4002 has a Reverse Breakdown Voltage somewhere above 100 volts. A Zener diode is constructed so that its Reverse Breakdown voltage is clearly defined and accurate. For example Reverse Breakdown voltage for a 1N4733 is 5.1 volts. A !N4734 is 5.6 volts.