zener diode theory and working as voltage regulator

1. ZENER DIODE

2. • Zener diode is a special purpose diode which can be used as a vpltage
regulator.
• In PN junction diode it has 2 operation condition
• 1)forward bias
• 2)reverse bias
• When we reverse bias the diode the current flows the diode due to
minority charge carriers
• Current due to minority charge carriers are constant for some values of
voltage

3. • If we further increase the voltage the current will be maximum .
• The point where the maximum current is obtained is called as reverse
break down voltage.
• And the sudden increase in the current has 2 reasons
• 1)Zener effect
• 2)avalanche effect
•
• Symbol

4. Zener effect
• In Zener effect
• The impurities are more
• Depletion layer is small
• Very low reverse bias voltage is required to break down the depletion
layer
• Electric field is more

5. Avalanche effect
• Impurities are less
• Depletion layer is large
• Large reverse bias voltage is required

6. ZENER DIODE AS A VOLTAGE REGULATOR

7. • The fluctuations in the input voltage Is known as irregular voltage.
• When the input voltage increases current passes through the series
resistance increases then the voltage drop across resistance increases
the drop is exactly equal to change in the input voltage we get constant
output voltage
• When the input voltage decreases current passes through the series
resistance decreases then the voltage drop across resistance decreases
we get the constant output voltage
• Every time output voltage remains constant across Zener diode what
ever may be the input voltage.