Zener diode , also called a voltage regulator diode, is a semiconductor device that has a high resistance until the critical reverse breakdown voltage. In the critical breakdown point, reverse resistance is reduced to a very small value, in the low resistance region in current increases while the voltage is kept constant, is classified according to the zener diode breakdown voltage regulator tube, because of this characteristic, mainly as a regulator or voltage reference element. The voltage stabilizer can be connected in series to be used at a higher voltage, and more stable voltage can be obtained through a series of series.
The zener diode is different from germanium diode. If the reverse voltage is sometimes referred to as "bias voltage", it will increase to a specific value. For a slight bias voltage, the current will increase appreciable. The voltage that causes this effect is called the "breakdown voltage" or "zener voltage". The breakdown voltage of the 2DW7 type tube is between 5.8 and 6.5V, and the maximum current is 30mA.
Working principle of Zener diode
In general the diode is reverse bias, if the voltage is more than PIV (peak reverse voltage) value when the diode will be destroyed, this is because the general diode at the ends of the potential difference is high under and through a large number of current power generated by the derivative of the heat is enough to make the diode burn.
Zener diode is designed in collapse area, has a good power dissipation device, can be used as a reference voltage or constant voltage component. If as a voltage regulator using a zener diode, which will enable the voltage to maintain in the vicinity of Vz and almost only a certain value, without carrying current or power supply voltage change effect.
Generally, the breakdown voltage of diodes can be controlled at will when making, so the voltage of Vz of Zener diode is generally from several volts to 100 volts. The general characteristics of Zener diode in the circuit or in addition to standard Vz, which can indicate Pz, led through the maximum current of Iz by Pz=Vz*Iz conversion.
Working principle
The main work in the reverse biased zener diode, diode reverse bias in the work in the area, when the previous voltage does not reach the breakdown voltage, the diode is not current, but when the reverse voltage reaches the breakdown voltage, each tiny voltage increase will produce considerable current, the voltage across the diode will remain in a a variation of voltage value is small (almost equal to the breakdown voltage), the zener diode current voltage curve, which should permit the above description.
General application circuit design description
When zener diode is used as a voltage regulator, it usually needs a series of step down resistance (R) to connect to the power supply, but the voltage source (E) must be higher than the breakdown voltage of the diode. Otherwise, the voltage stabilizing function of the diode will not be achieved.