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PNP as a clamp

tronicman

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hello guys,
i just want a piece of help, this PNP is used as a clamp and im strugling to calculate or to determine the clamp voltage at which the Vout will be clamped ,
thnx for helping me,
PNP clamp.png
 

FvM

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Silcon transistors have a typical BE reverse breakdown voltage of 7V. The transistor model in post #4 still shows no reverse breakdown at 14V, very unrealistic.
 

danadakk

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Silcon transistors have a typical BE reverse breakdown voltage of 7V. The transistor model in post #4 still shows no reverse breakdown at 14V, very unrealistic.
Excellent point, so I strapped a 4.7V zener to simulate the Vebo rating (datasheet I looked at
was 5.0 V) problem. Clearly spice model incomplete. As you can see clamp results very poor.


1607037898340.png


If I raise input R to 10 K -

1607037798981.png

Regards, Dana.
 

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