Zener Diode (=제너)

http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/zener-diodes/#DioEqu

▼Zener Diode Table(=제너다이오드 표)

▼잠시 이해를 돕는 그림들

(저항없이 Zener만으로 출력전압을 뽑으면, Zener가 과열된다.

(2A전원공급기를 연결했을때 붉은색을 띠며 타버렸다.))
(☆!!! 인가전압에 저항을 없애고 출력전압에 저항을 달경우 Junction에 전류가 정체된다.)

(Vin과 GND만 연결해도 Short현상이 발생한다.)

(부품 손상으로 연결되니 주의해야한다. (열은 발생하지 않는다.))

▲출력단에 Rectifier 사용을 권한다.

역전류로 인한 전압강하를 막아줄 수 있다.

▼Zener + Rectifier의 예

추력 전압이 Rectifier 전후로 다름을 알 수 있다.

https://electrosome.com/zener-diode-voltage-regulator/

▲전압강하를 시켜서 Regulator의 용도로 이용하기위해서는

부하저항 RL이 필요하다.

http://rayshobby.net/24vac-to-5vdc-conversion/

▲24VAC to 5VDC

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http://www.electronics-tutorials.ws/diode/diode_7.html

▲참고사이트

If we connect a diode and resistor in series with a DC voltage source so that the diode is forward-biased, the voltage drop across the diode will remain fairly constant over a wide range of power supply voltages as in Figure below (a).

According to the “diode equation” here, the current through a forward-biased PN junction is proportional to eraised to the power of the forward voltage drop. Because this is an exponential function, current rises quite rapidly for modest increases in voltage drop. Another way of considering this is to say that voltage dropped across a forward-biased diode changes little for large variations in diode current. In the circuit shown in Figure below (a), diode current is limited by the voltage of the power supply, the series resistor, and the diode’s voltage drop, which as we know doesn’t vary much from 0.7 volts. If the power supply voltage were to be increased, the resistor’s voltage drop would increase almost the same amount, and the diode’s voltage drop just a little. Conversely, a decrease in power supply voltage would result in an almost equal decrease in resistor voltage drop, with just a little decrease in diode voltage drop. In a word, we could summarize this behavior by saying that the diode is regulating the voltage drop at approximately 0.7 volts.

Voltage regulation is a useful diode property to exploit. Suppose we were building some kind of circuit which could not tolerate variations in power supply voltage, but needed to be powered by a chemical battery, whose voltage changes over its lifetime. We could form a circuit as shown and connect the circuit requiring steady voltage across the diode, where it would receive an unchanging 0.7 volts.

This would certainly work, but most practical circuits of any kind require a power supply voltage in excess of 0.7 volts to properly function. One way we could increase our voltage regulation point would be to connect multiple diodes in series, so that their individual forward voltage drops of 0.7 volts each would add to create a larger total. For instance, if we had ten diodes in series, the regulated voltage would be ten times 0.7, or 7 volts in Figure below (b).