Reverse polarity protection - proper TVS location

Kostyantyn Koziy1

Good day, dear engineers!

I am using simple PFET circuit to provide a reverse polarity protection. What is the proper way to protect PFET (and beyond) from ESD in this circuit? Assuming that BATT_12V is the source of ESD.

I saw both locations of D1 bi-dir TVS in app notes. IMO, it makes sense to put it before pFET.. no reason to put after, maybe just uni-dir version. Unless I don't understand something.

Thanks for the comments!

over 3 years ago

0 Sandesh Rawool over 3 years ago

TI__Intellectual 2694 points

Hi Kostyantyn,

Could you please re-attach the schematic image that you want us to review. It did not get attached properly. You can also use the insert file feature to upload the image.

Thank you,

Regards,
Sandesh

0 Kostyantyn Koziy1 over 3 years ago in reply to Sandesh Rawool

Prodigy 60 points

Thanks for the reply, Sandesh. I have updated the original post.

0 Matt Smith3 over 3 years ago in reply to Kostyantyn Koziy1

TI__Expert 8471 points

Hi Kostyantyn,

The rule of thumb for ESD protection diodes are that you want them to be as close to the connector/source of ESD events as possible. If TP2 and TP4 are the connectors that will be shocked, the bottom picture on your post will work better. Also, a unidirectional part would probably be better for this since it doesn't look like the circuit will be experiencing any negative voltages during normal operation.

Regards,

Matt Smith

0 Kostyantyn Koziy1 over 3 years ago in reply to Matt Smith3

Prodigy 60 points

Good day, Matt, thanks for the comment.

In my case, BATT_12V is the source of ESD. And the concern is that putting TVS after PFET may lead to PFET damage by ESD.
Nothing is perfect, but just wondering what solution would be better.

0 Matt Smith3 over 3 years ago in reply to Kostyantyn Koziy1

TI__Expert 8471 points

In that case, the top picture where the diode is to the left of the PFET would be best.

Regards,

Matt Smith

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Reverse polarity protection - proper TVS location