Zenor Diode Diode Applications

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Zenor DiodeDiode Applications
ES230 Jack Ou
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The Design of a Cell Phone Charger
Still need to be filtered to get a DC voltage
Output of the transformer
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Short for Positive Voltages and Open for
Negative Voltages
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Behavior of Ideal Diode
Ideal diode VanodegtVcathode Diode is
on VanodeltVcathode Diode is off An ideal current
experieincing VanodeVcathode, carries no current
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I/V Characteristics
An Open
A short
A diode
VanodegtVcathode Diode is on VanodeltVcathode
Diode is off An ideal current experieincing
VanodeVcathode, carries no current In practice,
consider a slightly positive or negative voltage
to determine the response of a diode.
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Example 1
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Example 2 An OR Gate Realized By Diodes
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In Class Exercise
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Example 3
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A Simple Cell Phone Charger Circuit
(R1 is necessary)
Another Application Signal strength indicator
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Rectifier Circuit as Signal Strength Indicator
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A Limiter Circuit
Question How do you modify this circuit so that
it passes only Positive portion of the waveform?
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Different Models of a Diode
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Choosing a Diode Model
Use the ideal model to develop a quick, rough
understanding of a circuit. If the ideal model
is not adequate, uses the constant voltage model,
which is sufficient for most cases.
Occasionally, we will use the exponential model
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Ideal Model versus Constant-Voltage Model
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Express ID1 and ID2 as a function of IS1, IS2 and
Iin.