TUSB522P: TX/RX pin swap / RX pin protection

Ryo Akashi

Genius 9470 points

Part Number: TUSB522P

Hello experts,

I got two question about TUSB522P from customer.

Customer plan to use TUSB522P (USB3.0) between PC and equipment connection because cable length will be long.

1. TX/RX pin swap

From schematic checklist (SLLA399), we can confirm TX pin and RX pin allow polarity swapping.

For example, there is no problem if we switch TX1P and TX1N. Is it correct?

If so, do we need to implement something special?

2. RX pin protection

TUSB522P will get power supply from one side (PC or equipment).

If one side is not working, TUSB522P can't get power supply.

In this case, another side may transmit some data to TUSB522P RX pin even TUSB522P can't get power supply.

Do they need to add some protection for RX pin?

Thanks and best regards,

Ryo Akashi

over 6 years ago

0 Malik Barton57 over 6 years ago

TI__Guru 64326 points

Hi Ryo,

1. This is correct nothing special need to be done. Polarity swap is taken care of USB Spec.

2. If TUSB522P is powered of the USB termination will not be present and no USB traffic will occur on the RX pins. Only when USB Host/Device sees USB termination will the USB handshake and traffic start.

0 Ryo Akashi over 6 years ago in reply to Malik Barton57

TI__Genius 9470 points

Hi,

Thank you for your comment.

Let me ask one thing.

You mentioned USB termination will not be present and no USB traffic will occur on the RX pins if TUSB522P is powered.

I think USB termination will not be present if TUSB522P is not powered. Is it correct?

Thanks and best regards,

Ryo Akashi

0 Malik Barton57 over 6 years ago in reply to Ryo Akashi

TI__Guru 64326 points

Hi Ryo-san,

This is correct if TUSB522P is not powered USB termination will not be present. Sorry my previous message has a typo.

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TUSB522P: TX/RX pin swap / RX pin protection