What Is The Difference Between Zener Diodes and Ordinary Diodes?

17 Jan 2020

Zener diode is a kind of diode used to stabilize the voltage and work in reverse breakdown state. It is mainly used in constant voltage source, auxiliary power supply and reference power supply circuit. In digital circuits, it is often used for level shifting; in overvoltage circuits, it is used for protection. Zener diode is a surface-contact crystal diode made of silicon material. Its symbol indicates that it is different from ordinary diodes.

The silicon zener is different from ordinary diodes, and its working range is just in the breakdown region.
The stabilizing tube can do this because it has the following two characteristics:
(1) Allowed to work in breakdown areas that do not exceed the maximum dissipated power
When working in the breakdown zone, as long as the reverse current through the tube is less than the maximum allowable current of the tube, or the power dissipated on the tube does not exceed the maximum dissipated power, the voltage stabilizer will not burn And it works fine.

(2) The voltage stabilizing tube has the characteristic of rapid breakdown under a certain voltage.

In layman's terms, it is a semiconductor component with a very high resistance until the critical reverse breakdown voltage. The zener tube has been working in the reverse breakdown region in the electronic circuit, so its connection mode is just the opposite of ordinary diodes.

As can be seen from the above figure, the voltage of the voltage regulator tube is almost constant within a certain current range, showing a very good voltage regulation characteristics, so it is widely used in electronic circuits.

The main parameters of the commonly used voltage regulator are as follows:
1.Stable voltage --- Uz within the stable range, the voltage on the voltage regulator.
2.Stable current --- Iz refers to the current value with the best voltage stabilization characteristic.
3.Maximum stable current --- Izm refers to the maximum current allowed when the Zener diode works.
4.Maximum dissipated power --- Pzm when the current is increased to a certain value Izm under the regulated voltage, the power at which the pipe is damaged by the heat emitted from the pipe.
5.Dynamic resistance Rz --- In the working area, the ratio of the change in voltage to the current at the two ends of the zener tube varies with the operating point. The smaller the value, the better.

The common parameters of ordinary diodes are:
1.Maximum rectified current Im, it refers to the maximum forward current value that the diode can pass under normal conditions for a long time.
2.Reverse current Ico, which refers to the DC current flowing through the diode when a reverse voltage is applied to the diode. Ideally, a diode has no single-phase conductivity due to its single-phase conductivity, but in practice it will have a small current flowing; the size of Ico reflects the quality of the single-phase conductivity of the diode, that is, the smaller the value of Ico is The better the single-phase conductivity.
3.Maximum reverse working voltage Urm, which refers to the maximum reverse voltage that the diode can withstand during normal operation. When the diode is connected in reverse, when the reverse voltage reaches a certain value, the reverse current in the diode will increase sharply, causing the diode to show a breakdown state. The voltage at this time is called the reverse breakdown voltage.
4.The highest working frequency Fm refers to the frequency at which the diode operates in the circuit. Due to the different manufacturing processes and materials and structures of the diode, the operating frequency of the diode is also different. The diode will severely heat up and lose its single-phase conductivity.

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