TUSB522P:

Ray Pourjalilvand

Part Number: TUSB522P

Tool/software:

Hello,

I have a related question about cascading USB redrivers. Please refer to the image below. There is already a USB redriver that has been implemented on the SBC card in one of the backplane slots. The USB3.0 signal has to travel several inches on the backplane and the Front IO board via an interface connector and then to the outside world via the Amphenol USB Type-A connector. I'd like to add another redriver, namely TUSB522P, on the IO board right before the Amphenol connector. Would just having two redrivers cause a jitter issue? I'd like to use a redriver rather than a retimer for it is less complex to use.

Does TI offer any USB retimers?

Thank you for your help.

Ray

/cfs-file/__key/communityserver-discussions-components-files/138/Redriver-Q.pdf

7 months ago

0 Vishesh Pithadiya 7 months ago

TI__Mastermind 42851 points

Hi Ray,

Unfortunately we do not have any USB retimers. It is possible to use multiple redriver sin the signal path, but you will need to make sure they are properly spaced out as not not violate the linearity region of the part.

0 Ray Pourjalilvand 7 months ago in reply to Vishesh Pithadiya

Prodigy 130 points

Hi Vishesh,

The SBC card where the existing USB redrivers are is a COTS card and we have no control over any of the equalization and emphasis taps. Do you have any suggestions on how I can set these taps on the new redriver I'm planning on putting on the Front IO board? Can you point me to a document where it explains the linear region of the redriver to give me some clues on how to make sure linearity region is not violated?

Thanks for your support.

Ray

0 Vishesh Pithadiya 7 months ago in reply to Ray Pourjalilvand

TI__Mastermind 42851 points

Hi Ray,

Here are the possible EQ and signal conditioning configurations of the part:

I recommend placing the redrivers at minimum 3dB away from each other to avoid over equalization. Using the PCB material we should be able to estimate the loss be inch of material in dB. Using this loss per inch value its best to keep the redrivers 3, 6, 9 dB away from each other.

0 Ray Pourjalilvand 7 months ago in reply to Vishesh Pithadiya

Prodigy 130 points

Hi Vishesh,

This is a closed chassis and it will be difficult to adjust the EQ, OS and DE taps via the external pull-up/pull-down resistors. Does TI offer a similar redriver in which these taps can be programmed via I2C or similar? I'm just thinking that opening the chassis and soldering and de-soldering these resistors and testing them each time may be troublesome. Doing it through software will be much easier.

Thanks

0 Vishesh Pithadiya 7 months ago in reply to Ray Pourjalilvand

TI__Mastermind 42851 points

Hi Ray,

The closest option would be the TUSB1004. However, this is a dual channel redriver.

+1 Ray Pourjalilvand 7 months ago in reply to Vishesh Pithadiya

Prodigy 130 points

Thanks for all your help, Vishesh. I'm going to close the ticket.

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TUSB522P: