Explain zener diode and its applications, Physics

 

ZENER DIODE: It is a two terminal semiconductor junction device with a very sharp voltage breakdown at reverse bias applied. The device is utilized to give a voltage reference. It is named after C. Zener, who first proposed electronic tunnelling as a mechanism of electrical breakdown in insulators. A Zener diode is a type diode that permits currents to flow in the forward direction like a normal diode, but also in the reverse direction in the voltage is larger than the rated breakdown voltage or “Zener Voltage”. It is sometimes called the breakdown diode. The breakdown diode may be silicon or germanium one but silicon is preferred over germanium because of higher operating temperature and current capability. The knee point is also sharper in case of a silicon diode. A zero diode exhibits almost the same properties as an ordinary diode except the device is especially designed so as to have a greatly reduced breakdown voltage, the so called Zener voltage. A Zener diode contains a heavily doped P-N junction allowing electrons to tunnel from the valance band of the P-type material to the conduction band of the N-type material. A reverse biased Zener diode will exhibits a controlled breakdown and let the current flow to keep the voltage across the Zener diode at the Zener voltage of 3.2v will exhibits a voltage drop of 3.2v if reversed biased. However the current is not limitless, thus the Zener diode is characteristically used to produce a reference voltage for an amplifier stage, or as a voltage stabilizer for low current applications. The breakdown voltage can be controlled rather precisely in the doping process. Another mechanism that generates a like effect is the avalanche effect as in the avalanche diode. The two types of diodes in the fact constructed the same way and both effects are present in diode of this type. In silicon diodes up to approximate 5.6v the Zener effect is the predominant effect and shows a marked negative temperature coefficient. At above 5.6v, the avalanche predetermined and exhibits a positive temperature coefficient. In a 5.6v diode the two effects occur together and then temperature coefficient nearly cancel each other out, thus 5.6v diode is the part of choice in temperature critical applications.

APPLICATIONS: Zener diode has numerous applications in transistor circuitry. Some of their general applications are:

(1)         Zener diode used as a Meter protection

(2)         Zener diode used as a peak clipper

(3)         Zener diode used as a reference element

(4)    Zener diode in switching operation has made possible an externally fast performance in computer applications.                       

The fundamental parameters of a Zener diode are:

The most ordinary range of Zener voltage is 3.3v to 75v. A tolerance of the specified voltage must be started. While the most popular tolerances are 5% and 10% more precision tolerances as low as 0.05% are available. The power managing capability should be specified for the Zener diode popular power ranges are 1/4, 1/2, 1, 5,10 and 50 watts.

 

Posted Date: 7/9/2012 1:46:05 AM | Location : United States







Related Discussions:- Explain zener diode and its applications, Assignment Help, Ask Question on Explain zener diode and its applications, Get Answer, Expert's Help, Explain zener diode and its applications Discussions

Write discussion on Explain zener diode and its applications
Your posts are moderated
Related Questions
Explain the Optical Instruments? The lenses you use most often are the ones in your eyes. The front of your eye has a convex lens whose focal length can be changed by the muscl

the weight of man is 50kg in earth what is weight of man 15% of its weight in moon

A 250V, 50Hz single-phase supply feeds the following loads (i) incandescent lamps taking a current of 10A at unity power factor, (ii) fluorescent lamps taking 8A at a power

A quantity that can be calculated by instrument, clearly defined and has proper units is known as physical value. Physical quantities are described as fundamental and derived quant

When a P-type semiconductor is suitably joined to an N-type semiconductor, then resulting arrangement is called P-N junction or P-N junction diode Depletion region : On account

The Doppler Effect shows that the spectrum of light from a visible body moving AWAY from the Earth will experience a shift in frequency when viewed from Earth. This definite s

Tungsten: Atomic number 74 Symbol W Atomic weight 183.85 Discovery Purified Tungste

The topic for the project is Newton's Law of Cooling, although you may choose a different title. The aim is to research how the temperature of a hot object is lost when it is kept

Q. A compound microscope consists of an objective lens of focal length 2.0cm and an eye piece of focal length 6.25cm separated by a distance of 15cm.How far from the objective sho

In a ripple tank two regions A and B can be created by introducing a pile of glass plates in region B. Thus region B is a shallow water region while region A is a deep water re