What is the state in which the Zener diode works when it is regulated

Reverse breakdown state.

What is a Zener diode? Zener diodes are also called "Zener diodes". When the PN junction is reversed to break down, its current can vary over a wide range and is stabilized at an almost constant voltage.

In fact, a Zener diode is a semiconductor device that has a high resistance before the reverse breakdown voltage. At this critical breakdown point, the reverse resistance drops to a very small value, at which point the current increases and the voltage remains constant.

According to the above figure, we can see that when U1=10V, the partial voltage on the RL DZ is 10 (500 (501000))=, and from the V I characteristics of the inverter, the voltage on the DZ is lower than the disconnect voltage, and the diode is in the disconnected position. A current of 0 1500 is equal to a resistance of 1K, and when the diode is turned off, the reverse operating current is much lower than 1mA, and the actual voltage of DZ RL is lower than the calculated voltage, taking into account the shunt of the regulator.

Assuming U1 is 25V, DZ will not be reversed. The voltage partial on the RL DZ is 25 (500 (501000))=, and from the point of view of the reverse V I, when the voltage at the DZ terminal exceeds the breakdown, the diode is in the reverse breakdown position. Contradicts assumptions.

So the diode works in a breakdown state and recalculates the voltage and current.

It is a stable voltage;

This is a voltage regulator diode that uses the phenomenon that the current can change over a wide range while the voltage remains basically unchanged in the reverse breakdown state of the PN junction.

This diode is a semiconductor device that has a very high resistance until the critical reverse breakdown voltage. At this critical breakdown point, the reverse resistance is reduced to a small value, in which the current increases while the voltage remains constant in the low-impedance region, and the Zener diode is binned according to the breakdown voltage, which is mainly used as a voltage regulator or voltage reference element.

Principle: The positive characteristics of the volt-ampere characteristic curve of the Zener diode are similar to those of ordinary diodes, and the reverse characteristics are that when the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is very large, and the reverse leakage current is very small.

However, when the reverse voltage approaches the critical value of the reverse voltage, the reverse current increases abruptly, called a breakdown, at which the reverse resistance suddenly drops to a very small value. Although the current varies over a wide range, the voltage across the diode is basically stable around the breakdown voltage, enabling the diode to be regulated.

It is the voltage value of the Zener diode that is reversed and stabilized, usually slightly higher than the (initial) breakdown voltage of the Zener Diode.

The voltage regulation value is the voltage value when the diode works in the reverse breakdown region, the current changes in a large range, and the voltage changes very little.

The voltage regulation value of the Zener diode refers to the stable voltage value generated at both ends of the Zener diode when the rated current is passed. This value varies slightly with the operating current and temperature. Due to the difference in manufacturing process, the voltage stabilization value of the same type of regulator tube is not completely consistent.

For example, the VZ of 1N4728A, the VZ of 1N4729A, the VZ of 1N4730A, and the VZ of Z1330A are 330V.

Zener diode 1N4728A-Z1330A

Regulator tubes. Working state: generally working in the steady state of reverse breakdown, in a certain current range (or in a certain power loss range), the terminal voltage is almost unchanged, showing voltage stabilization characteristics.

Function: After the regulator tube is connected to the circuit, if the voltage fluctuation of the power supply voltage or other reasons causes the voltage of each point in the circuit to change, the voltage at both ends of the load will remain basically unchanged. After the reverse breakdown of the regulator tube, although the current changes in a wide range, the voltage at both ends of the regulator tube changes very little.

Taking advantage of this characteristic, the regulator can play a role in stabilizing the voltage in the circuit.

A regulator diode (also known as a Zener diode) is a semiconductor device that has a very high resistance until the critical reverse breakdown voltage. Normal operation in the reverse breakdown state, as shown in the figure, there is a large current change voltage almost unchanged.

Regulator tubes. It is in the reverse breakdown state during normal operation, and the interval is recoverable. Don't make the mistake of thinking that just because you see the word breakdown, it's a broken device. The regulator tube is also a type of diode, and the diode is equivalent to a p-n junction.

It is made by using the characteristics of PN knots.

As shown in the figure below, is the volt-ampere characteristics of the p-n junction, where the first quadrant is located.

For the forward characteristic curve, the ordinary diode is developed using this characteristic, taking the general silicon diode as an example, its forward conduction voltage drop is about and around, when the forward voltage is applied to the diode, the diode is turned on, and the current of the diode after the conduction shows an exponential upward trend, that is to say, the current changes greatly and the voltage drop changes very little, when the reverse voltage is added to the diode, when the diode voltage is less than uz (reverse breakdown voltage), the reverse electric base trouser flow of the diode is very small, generally a or na order of magnitude.

Negligible, this is the characteristic of ordinary diodes with forward conduction and reverse cut-off.

Voltammetry characteristics of PN junctions.

Zener diodes.

The Zener diode works in the reverse breakdown zone, the reverse breakdown zone has a range, when the Zener diode is used, it must be made to work in the interval, izmin iz izmax, iz is the working current of the Zener diode, izmin is the minimum Zener current of the Zener diode, and izmax is the maximum working current of the Zener diode. Therefore, when using the voltage regulator diode, the parameter calculation of the current limiting resistance is also very particular, and the voltage stabilization effect may not be achieved if the design is not good, or the current is too large and the avalanche breaks down, resulting in the diode burning out! Its normal working area is shown in the yellow part of the front sail below.

Classical circuit of Zener diode: In practical application, the value of the current limiting resistor r is calculated according to the relevant parameters of the Zener diode (typical voltage regulation value, typical working current value, maximum working current, minimum voltage regulation current, input voltage range, output load current range).

Regulated diode circuits.

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The normal working state of the Zener diode is the reverse breakdown state.

The voltage regulator diode, also known as the "Zener diode", is that when the PN junction is broken down, its current can be changed in a wide range, and the voltage is almost unchanged. In fact, a regulator diode is a semiconductor device that has a high resistance before the reverse breakdown voltage, at this critical breakdown point, the reverse resistance drops to a small value, the current increases, and the voltage remains unchanged. The normal working state of the Zener diode is related to the model of the diode, and the value of the Zener diode is different for different models.

The volt-ampere characteristic curve of a regulated diode is similar to that of a general diode, and its reverse characteristics are as follows: when the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is higher, and the reverse leakage current is smaller. However, when the reverse voltage approaches a critical value, the reverse current suddenly increases, the so-called "breakdown".

Although the current varies widely, the voltage on the diode remains basically close to the breakdown voltage, so the diode has a stabilizing effect.

What to know about Zener diodes

The state of the Zener diode, also known as "working characteristics", is divided into working state and cut-off state, where the working state is the reverse breakdown state, and the cut-off state is the non-working state. The working state of the diode must be judged according to the working time and current of the diode. Such as:

The voltage regulation value of the Zener diode is volts, then it will be higher than the volt input voltage in the circuit, and the stable output is volts, if the input is lower than the volts, it will not work, which is its normal working state.

Below the breakdown voltage of the regulator, it has unidirectional conductivity like a normal diode. When the reverse voltage reaches the breakdown voltage of the Zener diode, it turns on. The resistance of the 6V regulator diode is large when the reverse voltage is below 6V, and it is on when it is equal to and above 6V.

In the circuit, it is always connected in reverse, and the positive pole of the regulator tube is connected to the negative pole of the power supply. The forward characteristics of the volt-ampere characteristic curve of the Zener diode are similar to those of ordinary diodes, and the reverse characteristics are that when the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is very large, and the reverse leakage current is very small.