PCS Electronics PCS Electronics - home page PCS Electronics  
RegisterSearchFAQAM & FM Radio transmitters shop UsergroupsLog in
TVS problem

 
Reply to topic    PCS-Electronics Forum Index » Schematics - help and ideas View previous topic
View next topic
TVS problem
Author Message
Guest






Post TVS problem Reply with quote
I have a 23v max Transient Voltage suppressor. My question is....can I put a resistor on it to allow it to be used on higer voltages because these things cost 5 dollars for one and I am not going to pay that much for a higher voltage TVS.
Sat Feb 22, 2003 3:23 am
Tech_man
Guest





Post Very easy question to answer to your TVS problem Reply with quote
The answer to your question is simple, YOU cannot use a resistor on a TVS because the currents drawn from the TVS are varying constantly with voltage changes. So you pretty much have to buy a higher voltage TVS. Sorry:( Here is what I mean E/R=I. Lets say the TVS is rated for a minimum voltage conduction of 12 volts at 5 amps and a MAX clamping voltage of 23 volts and will pull 18 amps at this voltage. You have 400 volts of surge, but the resistor used is only calculated for just 200 volts of surge.

E=200v-23v=177v drop to get 23v
I=18 amps
R=9.83 Ohms

Now the 400 volts:

E=400v-23v=377V
I=38.3 amps (Opps did I just see smoke and flames and here popping:P )
R=9.83 Ohms

So the conclusion to this is, its better to waste $5 on a higher voltage TVS rather than buying more because of the fried ones you keep getting.
Tue Feb 25, 2003 2:23 am
Display posts from previous:    
Reply to topic    PCS-Electronics Forum Index » Schematics - help and ideas All times are GMT + 1 Hour
Page 1 of 1

 
Jump to: 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group