Special purpose diode


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  • Fig. 3-9 Simple zener diode reg. circuit & label zener terminals
  • Fig 3-3
  • Fig 3-2 b zener curve
  • Fig 3-16a,b,&c
  • Special purpose diode

    1. 1. Basic Electronics Well Come This presentation on zener diode 19092 Khan.Xubair
    2. 2. Outlines Introduction of Zener Diode Construction of Zener Diode Working of Zener Diode Application of Zener Diode Numerical of Zener Diode
    3. 3. IntroductionThe zener diode is a silicon pn junction devices that differs from rectifierdiodes because it is designed for operation in the reverse-breakdownregion. The breakdown voltage of a zener diode is set by carefullycontrolling the level during manufacture. The basic function of zenerdiode is to maintain a specific voltage across it’s terminals within givenlimits of line or load change. Typically it is used for providing a stablereference voltage for use in power supplies and other equipment.
    4. 4. Construction of ZenerZener diodes are designed to operate in reverse breakdown. Two types of reversebreakdown in a zener diode are avalanche and zener. The avalanche break downoccurs in both rectifier and zener diodes at a sufficiently high reverse voltage. Zenerbreakdown occurs in a zener diode at low reverse voltages.A zener diode is heavily doped to reduced the breakdown voltage.This causes a very thin depletion region. The zener diodes breakdown characteristics are determined by thedoping processZeners are commercially available with voltage breakdowns of 1.8 Vto 200 V.
    5. 5. Working of ZenerA zener diode is much like a normal diode. The exception being is that itis placed in the circuit in reverse bias and operates in reverse breakdown.This typical characteristic curve illustrates the operating range for a zener.Note that it’s forward characteristics are just like a normal diode.
    6. 6. Breakdown CharacteristicsFigure shows the reverse portion of a zener diode’s characteristiccurve. As the reverse voltage (VR) is increased, the reverse current (IR)remains extremely small up to the “knee” of the curve. The reversecurrent is also called the zener current, IZ. At this point, the breakdowneffect begins; the internal zener resistance, also called zener impedance(ZZ), begins to decrease as reverse current increases rapidly.
    7. 7. Zener diode Data Sheet Information VZ: zener voltage IZT: zener test current ZZT: zener Impedance IZK: zener knee current IZM: maximum zener current
    8. 8. Ideal Model & Ideal Characteristic Curve of Zener Diode
    9. 9. Practical Model & Ideal Characteristic Curve of Zener Diode
    10. 10. Zener Diode Applications –Zener Regulation with a Varying InputVoltage
    11. 11. Zener LimitingZener diodes can used in ac applications to limit voltage swings todesired levels. VZ: zener voltage Vd: Diode voltage Vd = 0.7
    12. 12. Numerical of Zener Diode
    13. 13. The end……. Thank You…..