TVS proper power Rating?

[rocky79]

Hello fellows,

Looking for some help choosing the proper TVS. I am mainly concerned with the power rating.
The requirement calls for a maximum transient of 600v for 2 us as shown below.

The circuit to protect operates at 28Vdc and the initial current draw can be up to 150mA and then drops down to few mA.
(Input protection circuit)

My question is how to determe the proper power rating for the TVS?
For testing purposes if a 600 volts peak voltage is applied with a 50 ohms source impedance as stated on the chart, would the short circuit current be 12 amps?

I guess that’s the missing information that I would be looking for then the TVS peak power dissipation should be 600vx12 amps=7.2kw?

Thank you in advance.

 

[kam1787]

I think you forgot the time element;

**broken link removed**
https://pml.nist.gov/spd-anthology/files/MOV_announce_BW.pdf

 

[dick_freebird]

You may be looking more for a Joule energy rating, the TVS
should not be handling power for anything but abnormal brief
events. Of course you need to handle the power too, but in
my limited experience the energy is the big deal when you
get to short timescales and conduction then can't help you.

 

[rocky79]

Thank you for your replies, however I still have the same question. How many watts should the TVS be?
I found an Appnote by microsemi, I thought I would go with the TVS power approximation Ppp of 5000W.
What do you guys think?