TUSB7340: PCIE and USB Superspeed Polarity Swapping

Girish Ramful

Part Number: TUSB7340

Tool/software:

Hi there,

From the TUSB73x0 Board Design and Layout Guidelines (Rev. E) - Section 5.4 & 7.2, the PCIe and Superspeed differential pairs can swapped their polarity (P/N).

Will the chip automatically detect this polarity change? or is it a software change to reflect the polarity swap?

Thank you,

Girish

5 months ago

0 Brian Zhou 5 months ago

TI__Guru*** 129855 points

Hi GIrish:

For USB3, polarity swap is allowed by USB3 spec.

For PCIe polarity , I need to check if it's allowed ot not.

Best

Brian

0 Brian Zhou 5 months ago in reply to Brian Zhou

TI__Guru*** 129855 points

For for late reply, For PCIe, polarity swap is alllowed too.

Best

Brian

0 Girish Ramful 5 months ago in reply to Brian Zhou

Prodigy 30 points

Hi Brian,

Thank you for information.

For the PCIe polarity swap, is allowed by the PCIe spec or is it a software change?

Also, I am planning to swap the polarity only for the TX signals. Should the RX signals be polarity as well? or they are independent of the TX polarity swap?

Sincerely,

0 Brian Zhou 5 months ago in reply to Girish Ramful

TI__Guru*** 129855 points

It is allowed by PCIe spec.

You can swap only for TX or RX or swap for both.

Best

Brian

0 Girish Ramful 5 months ago in reply to Brian Zhou

Prodigy 30 points

Thank you very much for your support!

Sincerely,
Girish

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TUSB7340: PCIE and USB Superspeed Polarity Swapping