HD3SS3412A: AC coupling placement

user6065602

Part Number: HD3SS3412A

Hi,

Concerning the AC coupling, is there a recommendation concerning the AC coupling position?

1) After the IC's Tx and before the muxes.

2) After the muxes, near the connector.

3) Other.

Also, what is recommended on the board placement for the ac coupling cap? Near the Tx of the device or near the PCIe connector?

Thanks!

0 Brian Zhou over 4 years ago

normally AC caps are placed on TX lanes close to connector side.

0 user6065602 over 4 years ago in reply to Brian Zhou

Do you mean the following: TX -> muxes (HD3SS3412A)-> AC caps -> connector.

Can you please explain why this configuration could be an issue: Tx -> AC caps -> muxes - Connector

0 Brian Zhou over 4 years ago in reply to user6065602

I don't think it's an issue for TX-AC-Muxs-Connector, we just prefer the other way.

0 user6065602 over 4 years ago in reply to Brian Zhou

Any reason for that preference?, it can demand twice more caps on the design and also just by curiosity is there an application note about that?

0 Brian Zhou over 4 years ago in reply to user6065602

it can protect the high Vcm from the other side of the connector. For 3412, Max Vcm is 2v.

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