Hi,
I have a circuit where I need to implement surge and ESD protection. After a whole day of googling and reading I still need some advice. I have attached a very simple sketch showing the two points that will be exposed and therefore need protection - a 12V net and some 3.3V nets. So to the questions:

1: It seems that the most common solution is to use a TVS-diode, is that correct? Are there other solutions that could work well for these applications?
2: Given TVS-diode is used. Is it correct that Vr should be as close to the operating voltages (12V and 3.3V) and that the V_clamping should as close to, but not above, the absolute maximum rating (16V and 3.6V)?
3: Unidirectional or bidirectional? As far as I can tell they should be unidirectional.
4: Why is it so hard to find components? With the specs from point 2 and 3 I find exactly zero items on Digikey, even though they have over 90k components in the TVS-diode category.

Any help is largely appreciated!

 

Hello,

As far as I know there are no TVS diodes lower than 5 Volts.
See the attached documentation for more info.

Bertus

 

Thanks,
It looks like Digikey has diodes rated as low as 1V, however none with 3.6V clamping voltage, and none that has around 16V clamping voltage combined with 12Vr.

 

Hello,

I think that the physics of the TVS diodes do not allow such a small difference between the knee-voltage and clampling voltage.

Bertus

 

That sounds like it could make sense! Do you know of any other options when it comes to surge and ESD protection in this case?

 

http://www.infineon.com/dgdl/AN248....7042f&fileId=db3a304332ae7b090132b51636813063
http://www.vishay.com/docs/88440/failurem.pdf

 

http://www.infineon.com/dgdl/AN248....7042f&fileId=db3a304332ae7b090132b51636813063
http://www.vishay.com/docs/88440/failurem.pdf

Thanks,
The link to infineon.com returned 404. Regarding the doc about failure modes, could you please provide some context/relevance? Is it meant as general knowledge about the subject, or a solution to my issue? If it's the latter I am struggling to see how.

-Erik

 

Hello,

@Delta prime , the first link does not work.
The AN248 can not be found on the site.

Bertus

 

My apologies do not wish for you to struggle any more than you have to. Try this in reference to your application https://electronics.stackexchange.com/questions/483959/how-does-esd-protection-work-with-tvs-diodes.

 

My apologies do not wish for you to struggle any more than you have to. Try this in reference to your application https://electronics.stackexchange.com/questions/483959/how-does-esd-protection-work-with-tvs-diodes.

Thanks for your reply,
That thread talks about the difference between TVS and rail clamp (which apparently needs power supply to work), however I can't see how it answers any of my questions. (Interesting read though).

-Erik