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

11 months ago

0 Brian Zhou 11 months ago

TI__Guru*** 146735 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 11 months ago in reply to Brian Zhou

TI__Guru*** 146735 points

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

Best

Brian

0 Girish Ramful 11 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 11 months ago in reply to Girish Ramful

TI__Guru*** 146735 points

It is allowed by PCIe spec.

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

Best

Brian

0 Girish Ramful 11 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