HD3SS3220: AC Coupling Capacitor Requirements

Matt Calvo

Part Number: HD3SS3220

Hey USB Interface team,

I have a customer evaluating the HD3SS3220 for a new design and we were hoping to get your guidance and recommendation on where AC coupling capacitors are required in the USB analog signal chain interface. Please refer to the diagram below for reference:

We believe that AC coupling capacitors are required at locations C and D and would assume that AC coupling capacitors are required between the Host Controller and Mux at locations A and B as well, but seen conflicting recommendations online for other USB-C SuperSpeed muxes.

Any guidance you can provide on this would be greatly appreciated!

Best regards,

Matt Calvo

over 1 year ago

0 David (ASIC) Liu over 1 year ago

TI__Guru**** 154921 points

Matt

The HD3SS3220 high speed signal pins common mode voltage is from 0 to 2V. If the host controller common mode voltage can meet the HD3SS3220 common mode voltage, then

A and B will be DC coupled.
RX1 and RX2 can be optionally AC coupled with 330nF or DC coupled,
TX1 and TX2 must be AC coupled with 0.1uF or 0.22nF caps

Thanks

David

0 Matt Calvo over 1 year ago in reply to David (ASIC) Liu

TI__Genius 14055 points

Thanks for the quick reply David!

I'll go ahead and relay this information to my customer and will have them comment back on this thread with any follow-up questions they may have.

Have a great weekend!

Best regards,

Matt

0 David (ASIC) Liu over 1 year ago in reply to Matt Calvo

TI__Guru**** 154921 points

Matt

No problem, I will go ahead and close this thread for now. The thread will re-open once you provide new comment to it.

Thanks

David

0 Liam Mulshine over 1 year ago

Prodigy 20 points

It appears that the TX and RX pins on this part are bidirectional. Considering this, is it OK to swap TX and RX if they are swapped on both sides of the mux? See snippet below as an example:

0 David (ASIC) Liu over 1 year ago in reply to Liam Mulshine

TI__Guru**** 154921 points

Hi,

It is possible to swap its TX & RX pins, you only have to care about the appropriate routing direction between the HOST and the USB connector.

Thanks

David

0 Liam Mulshine over 1 year ago in reply to David (ASIC) Liu

Prodigy 20 points

Thanks for confirming!

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HD3SS3220: AC Coupling Capacitor Requirements