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Voltage Barrier

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Opticalworm:
Hello everyone,

I'm trying to design a voltage barrier using a quick blow fuse and a TVS Diode (See attachment). Does anyone know what sort of parameters should I be looking for on quick blow fuses and TVS diodes?

From What I gathered, Under normal condition the TVS diode is inactive when the supply voltage is less then the breakdown voltage of the diode (Vrb) and If the supply voltage goes above the diode's Vrb then it becomes active and starts the conduct, which in turns, short circuits the supply to ground. As long as the fused is selected so that it blows before diode reaches the peak current (Ipp), for a set time, then the Diode should be safe.

What you think?

Btw,the design is for an Intrinsically safe certification (class ia)

Simon:
look up TVS diode on wikipedia, it has a nice explanation of all of the voltages that make up a TVS's spec (yes there are a few and I neb=ver remember the right names)

tyblu:

--- Quote from: Simon on February 17, 2011, 06:32:02 am ---...I neb=ver remember...
--- End quote ---
"b" and "=" are not right beside each other on the keyboard. wtf mate. Was that a "vb" finger mash, then a <backspace> miss, hitting "=" instead, followed by an instinctive <enter>, sealing the deal? I want a play-by-play.  :D

Simon:
yea I think you figured it out, obviously I didn't  ;D

Opticalworm:

--- Quote ---look up TVS diode on wikipedia, it has a nice explanation of all of the voltages that make up a TVS's spec
--- End quote ---
Thank you Simon, but I've already been wikipedia about TVS diode unfortunatly its don't really go into as much detail as I would have hoped.

Here a better source by microsemi about TVS diodes. http://www.microsemi.com/micnotes/125.pdf.

I don't think my original question was clear enough. Sorry. I was hoping that someone knows how to match a fuse with a TVS (or zener) diode in such way that the fuse will blow before the diode, which in turn, protects the connected circuit from over voltage.

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