TUSB7320EVB - Polarity swapped in the EVB schematic

Kawai

Guru 19775 points

Hi Team,

Please let me ask you about the TUSB7320EVB schematic.

I am looking at the User's Guide : TUSB73x0 Board Design and Layout Guidelines.

In the schematic of this document in page 38, I see some signal connection which polarity are swapped. Please see the below for the swapped signals.

[Q1]
Is this the correct connection for this device ? why are they swapped ?

[Q2]
Our customer had designed their board without swapping the signals. I believe non-swapping connection would be the correct way for the connection but if the user did not swap the polarity would there be any problem ?

Best Regards,

Kawai

over 9 years ago

0 Diego Cortes over 9 years ago

TI__Mastermind 36085 points

Hello Kawai-san,

This is not an issue, since the USB3 spec allows the polarity inversion. During the TSEQ training sequence, the receiver must detect a possible polarity inversion in its input channel; if so, then the receiver shall invert the polarity of all the received bits. (Please see the section 6.4.2 of the USB3 specification, page 141).

Best regards,

Diego.

0 Kawai over 9 years ago in reply to Diego Cortes

Guru 19775 points

Hi Diego-san,

Thank you for your answer.

I understood that the USB 3.0 spec allows USB data line polarity inversion.

Please let me confirm about the PCIe side.
Does it also allows the polarity inversion at the PCIe side too ? (for PCIE_REFCLK and PCIE_TX)

Best Regards,
Kawai

0 Elias Villegas M. over 9 years ago in reply to Kawai

TI__Guru* 76130 points

Yes,

PCIe allows for polarity swap as well.

Regards.

0 Kawai over 9 years ago in reply to Elias Villegas M.

Guru 19775 points

Hi Ellias-san

Thanks for the answer.

Best Regards,
Kawai

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TUSB7320EVB - Polarity swapped in the EVB schematic