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Zener Diode vs. TVS Diode

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ata90

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Are there any difference between TVS diode and Zener Diode or both devices are same?
if TVS diode is something else, can you name some models?

Thank you
 

betwixt

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They are very similar but nt the same. A Zener diode behaves like a normal diode in the forward (conducting) direction, it's rated 'zener' voltage is the reverse breakdown voltage. A TVS doesn't conduct in either direction until it's breakdown voltage is reached. You can think of a TVS are being two Zener diodes in series, pointing in opposite directions.

Brian.
 

ata90

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can you please name some models of this kinda diode?
 

ata90

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Please notice the parts shown by red-rectangle bellow.
Are these parts good enough to protect MOSFET from transient over voltage and over current?
 

s.manikandan

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zener will works under reverse bias condition and you will get the constant voltage across it when you bias it.
TVS is nothing but,transient voltage suppressor,in SMPS for dissipate the leakage inductance energy in the transformer ie.,just like a snubber diode.
 

FvM

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You can think of a TVS are being two Zener diodes in series, pointing in opposite directions.
Your despription applies only to bidrectional TVS diodes. But you get unidirectional TVS diodes as well, which are in fact nothing but power Z-diodes.
 

ata90

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zener will works under reverse bias condition and you will get the constant voltage across it when you bias it.
How about my work? is it configure correctly for over voltage and over current suppression?
 

FvM

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There's no overcurrent protection (e.g. to handle motor short or stall) in your circuit and it won't be easy to achieve.

The free wheeling diode is essential, the TVS diodes are not neccessarily required and may possibly affect the cicuit performance.

Vds overvoltage is also limited by the FET avalanche breakdown capability (up to a certain energy level). Vgs overvoltage should be strictly avoided, but as long as the driver supply is properly bypassed, it won't occur. The 100 ohm series resistor will increase switching times and increase losses, a problem with higher PWM frequencies.

By the way, tt's not clear how the high side driver can work in the shown circuit.
 

mtwieg

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It's not quite correct to say that normal zener and TVS diodes are the same. TVS diodes are engineered for withstanding extremely high peak-to-average power. And in my experience, I've found that TVS diodes work poorly for simple low-power clamping applications where you would normally use a zener diode. They tend to have much higher zener impedance at low signal levels.
 

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