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TUSB522P: USB 3.1 Gen 1 ReDriver EQ/DE/OS Optimization Procedure

Kyle Smith12
Prodigy 20 points
Part Number: TUSB522P
Other Parts Discussed in Thread: TUSB8020B

Hello,

I am currently looking to incorporate the TUSB522P into a USB 3.1 Gen 1 transmission line with an expected high insertion loss between two TUSB8020B hubs.

1. Per answers in threads such as this one, it appears that the method to determine the right selection of EQ/DE/OS settings is to choose conservatively and work from there in the absence of concrete simulation data. In your experience, is a protocol analyzer or simulation model really needed here for the integration of this product to be effective?

2. In this forum question, a customer asked if "it a good idea to place a hub part downstream from the host in an effort to "retime" the USB channel, possibly also putting redriver parts on both sides of the hub," but it looks like there wasn't an answer given. Assuming the region contributing to the insertion loss is known and discrete, would it be preferred to have a redriver before, after, or on both sides?

3. In this forum question, it was stated that "the usage of two or more re-drivers (especially for USB3) may cause over equalization issues." Is there a method to determine when this will be the case?

Thank you for your time and best regards,

Kyle

  • 0
    TI__Guru 64326 points

    Kyle,

    1. Protocol analyzer or simulation models and other advanced equipment are useful when debugging a specific problem. For general purpose debug however a oscilloscope and eye diagrams should give enough insight into the condition of the signal.

    2. Retimers are mainly used to clean up/remove jitter related noise from a signal. Redrivers and our USB Hubs do not have this capability. It would be best to place a redriver after this region as pre-channel, trace before the device has better compensation than the post channel. (See figure below)

    3. We do not have a method to determine this as it is dependent on the specific trace loss in your application. This is a general rule of thumb but if you anticipate loss greater than the maximum DC and or AC gain provided by one redriver using a second redriver is suggested.

    I would try to obtain an S-parameter model for your trace so that you can anticipate the loss per inch at the desired frequency.

  • 0 in reply to Malik Barton57
    Prodigy 20 points

    Hi Malik,

    Thank you for the quick and complete answers. I do have one follow up question in regards to the following statement:

    "Retimers are mainly used to clean up/remove jitter related noise from a signal. Redrivers and our USB Hubs do not have this capability."

    Is it correct to say that TI currently does not have a signal conditioning product capable of doing this aside from host controllers?

    Thanks,

    Kyle

  • 0 in reply to Kyle Smith12
    TI__Guru 64326 points

    Kyle,

    TI does have retimers for many applications, typically in video media. Also in my previous post I was incorrect USB Hubs can remove jitter as these devices have there own internal self referenced clock.