Zener diodes are mainly used as voltage sources.
Since they provide a reasonably constant voltage drop, even when current changes, they are useful in small power supplies as voltage regulators.
The main application of zener diode is, it is acts as a voltage regulator in reverse bais condition.Well compared to pn junction diodes the percentage of doping is high in zener diode.so, current is produced in the order of milli amperes even it is reverse baised.if reverse bais is increased zener breakdown occurs and allows constant voltage through it thus it acts as a "voltage regulator."
Zener diodes differ from normal p-n junction diodes in that they have a reduced reverse breakdown voltage and, in fact, we normally operate zener diodes in reverse bias to take advantage of the relatively stable voltage regulation it provides.
A typical diode functions only in one direction (forward-bias). When subjected to reverse-bias, the junction will eventually break down under high enough voltage. A zener diode works the same way, but breaks down at a very specific reverse-bias voltage. This is called its zener voltage. Because of this property, a zener diode can be used to regulate the voltage in a circuit. When inserted the opposite orientation as you typically expect a diode, it begins to conduct when the voltage across it reaches the zener voltage. Then the voltage stays at that level. See http://en.wikipedia.org/wiki/Zener_diode for more information.
yes if you add two 20V/1W zener in parallel you will arrive 20V/2W
You can use most diodes for that purpose, and particularly silicon diodes. However, you should not use zener diodes and similar for rectification purposes. Otherwise, you will likely not get the intended result. If the voltage exceeds the avalanche voltage, then the zener diode will no longer rectify, but conduct the other way as well.
A diode (some people incorrectly call them rectifiers) is a semiconductor device that allows a current to flow in one direction. A Zener diode allows a reverse to current to flow at a defined voltage. A common application for them is as a voltage regulator. Named for C M Zener , US Physicist. A zener diode is a diode and like all diodes it will conduct in both directions. If a reversed voltage is applied it will breakdown and conduct current. Most diodes when they breakdown the reversed voltage cannot be predictable. However a zener diode when they do breakdown in the reverse voltage mode that voltage can be made as predictable and remain +/- % of the breakdown voltage. Therefore this steady voltage can be used as a regulator for instance or a definite voltage drop if need be.
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).
Zener diodes are a form of semiconductor diode that are widely used in electronics circuits as voltage references. Zener diodes provide a stable and defined voltage and as a result Zener diode circuits are often used in power supplies when regulated outputs are needed. Zener diodes are cheap and they are also easy to use and as a result they are used in many applications and many circuits.
First off, I don't know if by current flow you mean conventional current flow or electron current flow. You realize they are in opposite directions and most electronics engineers use conventional current flow in circuit analysis.Ignoring this, I will assume your real question is "Why does current flow backwards in zener diodes compared to ordinary diodes?" The answer is that zener diodes are not operated in the forward biased range as are ordinary diodes, instead they are operated in the reverse biased range. When reverse biased enough any diode reaches breakdown voltage and suddenly conducts. Most ordinary diodes can be destroyed by breakdown, but zener diodes are designed to tolerate it. In zener diodes, this breakdown is referred to as "zener breakdown" and the voltage it happens at the "zener voltage".Low voltage zener diodes can still be used in the forward biased mode, like ordinary diodes. However most high voltage zener diodes have a "blocking diode" that is not documented on the data sheet to block forward biased operation. "Blocking diodes" are simply ordinary diodes wired in series with the zener; when the zener would be forward biased they are reverse biased (and thus blocking current), when the zener would be reverse biased they are forward biased.
Zener diodes are normally operated in their reverse breakdown voltage curve.
You do not want to replace diodes with zener diodes. They are not the same type of device, and the design objective is not the same.
The difference between the pn-junction diode and the zener diode is that the pn-junction diode is used for rectification while the zener diode is used for rectification and stabilization. Also, the zener diode can function in the breakdown region while the pn-juntion diode can not function in that regime.
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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.
Zener diodes differ from normal p-n junction diodes in that they have a reduced reverse breakdown voltage and, in fact, we normally operate zener diodes in reverse bias to take advantage of the relatively stable voltage regulation it provides.
By varying doping levels ,it is possible to produce zener diodes with varying breakdown voltages.
There are so many different types of diodes. Some of the common examples include light emitting diodes, silicon diodes, zener diodes and so many more.
If the zener diode is in zener breakdown the voltage across the zener diode remains constant regardless of current (for the ideal zener diode). Real zener diodes have parasitic resistance that causes the voltage across the zener diode to increase slightly with increased current, but due to temperature dependant variations in this parasitic resistance as well as temperature dependant variations in the zener breakdown voltage, this change in voltage in real zener diodes cannot be described by a simple linear factor.