Zener Voltage Regulator.

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Zener Voltage Regulators

• CEC

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Contents

• Block Diagram of a Power Supply.
• Zener Diode Characteristics.
• Unloaded Zener Voltage Regulator.
• Loaded Zener Voltage Regulator.
• Zener Regulator Design.
• Line Regulation and Load Regulation.

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Power Supply

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Zener Diodes

• Special diodes optimized for operation in the
  breakdown region.
• Connected in parallel with the load of the power
  supply.
• Zener voltage remains constant despite load
  current variations.
• Voltage regulation is the most common
  application.

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Zener Diode V/I Characteristics

• Zener diode acts like an ordinary silicon
  rectifier diode when forward biased.
• Forward voltage drop of about 0.7 V when
  conducting.
• In the reverse-bias region, a small reverse
  leakage current flows until the breakdown voltage
  reached.
• Reverse current (zener current) increases sharply
  beyond breakdown.

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Zener Diode V/I Characteristics

• Breakdown voltage remains nearly constant as the
  zener current increases.
• Zener Voltage VZ remains constant even though
  zener current IZ varies over a wide range.
• Zener diode can be used in voltage regulation
  circuits.
• Zener voltage VZ specified at a test current IZT.

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Zener Diode V/I Characteristics

Current rises sharply beyond breakdown voltage
Behaves like an ordinary diode
Very small current
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Power Rating of a Zener Diode

• Zener power dissipation PZ VZIZ
• PZ - power dissipated by the zener diode,
• VZ - zener voltage, IZ - zener current.
• Power dissipated in a zener diode must always be
  less than its power dissipation rating PZM.
• Maximum current that a zener can safely handle

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Unloaded Zener Regulator
Vin Vout dropped across Rs
IS
Is Iz
No Load Resistance
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Loaded Zener Regulator
IS IZ IL
Load Resistance
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Zener Regulator with Adjustable Load
Variable
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Zener Voltage Regulator Design

2.4K
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Zener Voltage Regulator Design

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Zener Voltage Regulator Design

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Zener Voltage Regulator Design

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Zener Voltage Regulator Circuit Diagram

, 0.5 W
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? indicates change.
VNL No load output voltage. VFL - Output
voltage under full load.
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Other Regulators

• Transistor Voltage Regulators Series and Shunt.
• Buck, Boost and Buck-Boost Regulators.
• IC Fixed Voltage Regulators - IC 78xx (positive)
  and IC 79xx (negative) (5V to 15 V).
• Adjustable (Variable) Voltage Regulators using
  ICs LM 317.

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Thank You