Zener Diode & Its Applications
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Transcript of Zener Diode & Its Applications
Zener Diode & its Applications
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Zener Diode
• This is a diode designed with adequate power dissipation capabilities to operate in the breakdown region.
• When both sides are heavily doped, the depletion layer is very thin (100 Ǻ).
• Even 4 V may give a field of 107 V/m, causing breakdown.
• Whatever may be the breakdown phenomenon, it is called ‘zener diode’.
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Equivalent Circuits
Rz
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v By controlling the thickness of the depletion layer, Zener Diode can be made to have breakdown at a specified Zener Voltage.
v Generally Zener Voltage ranges from 0 volts to 200 volts.
v As long as the current through the diode is limited by the external resistance in the circuit within permissible values, it does not burn out.
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Zener Diode Applications
1. Voltage Stabilizer or Regulator.2. Peak Clipper.3. Switching Operation.4. Reference Element.5. Meter Protection.
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Voltage Regulator
It has the ability to maintain a constant output even when either the input voltage or load varies.
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• A voltage regulator provides a constant voltage from a source whose voltage may vary appreciably.
Zener Diode 9 गु�वार, 11 फरवर�2010
Example
Zener Diode 10 गु�वार, 11 फरवर�2010
Zener Diode 11गु�वार, 11 फरवर�2010
• This voltage (82.5 V) is more than VZ (= 60 V).
• Hence, diode is ‘ON’.• Replace the diode by its equivalent.
Zener Diode 12 गु�वार, 11 फरवर�2010
Zener Diode 13 गु�वार, 11 फरवर�2010
Zener Diode 14 गु�वार, 11 फरवर�2010
Zener Diode 15 गु�वार, 11 फरवर�2010
This is more than VZ. Hence diode is ‘ON’. We now calculate the minimum value of zener current.
Zener Diode 16 गु�वार, 11 फरवर�2010
Zener Diode 17 गु�वार, 11 फरवर�2010
When V1 becomes 120 V :