TVS diode

[Rajinder1268]

Hi all,
I have attached a picture showing 2 different methods of using bidirectional TVS diodes to protect the CC1 pin of a USB C connector. Note I have the same for CC2.
I am not sure which one is better suited for this application.
Also why are the diodes facing differently on the two devices, does that make a difference?

 

[std_match]

The internal order of the diodes doesn't matter. It is enough to look at the electrical data in the datasheet.

 

[betwixt]

But do note that a true two diode solution requires them both to be Zener types. A Zener diode clamps in one direction and conducts normally in the other so the two together effectively clamp at Vz+Vf. A TVS is constructed to conduct in both directions beyond clamp voltage so their function is almost identical. The symbols are not important, I think they both convey the same meaning.

Brian.

 

[Rajinder1268]

My other question was the selection parameters for the TVS diode. The CC1 and CC2 signals can be anywhere between 3V to 5.5V.
The TVS diodes that I am looking at have a reverse standoff voltage of 5.5V.

This ideally should be higher than the signal level that requires protection. Is this going to be a potential issue?

Lastly, CC1 is rated to 1.25A and CC2 to around 0.25A. How do I select the IPP rating for the TVS diode based on this?

 

[FvM]

Consider that TVS diodes can provide protection against ESD and some surge events but not e.g. longer enduring overvoltage. In so far you are looking mainly for pulse current characteristic and rating.