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SN65LVPE502A: cascading two of them on different boards

Luca Rigazio
Prodigy 70 points
Part Number: SN65LVPE502A
Other Parts Discussed in Thread: TUSB522P, TUSB501

Hello,

In my system there are two USB3 lanes built in this way:

------------------------------------------

COMEX module:

1)  USB3 host (Intel chipset)

2)  COMEX connector

------------------------------------------

Carrier board:

3) COMEX connector

4) SN65LVPE502A redriver

5) Samtec connector

------------------------------------------

I/O board:

6) Samtec connector

7) CM choke + TVS diodes

8) USB3 I/O Connector (rugged)

------------------------------------------

9) 3 meter USB3 cable

------------------------------------------

10) USB3 device (USB key, SDD, etc.)

------------------------------------------

Since I'm in trouble with a few devices when using a 3 meter cable (and not with a short 30 cm cable), I'm considering the option of inserting a second redriver on the I/O board between 6) and 7) (I'd prefer not to redesign the carrier).

Question #1: is it meaningful such a solution?

Question #2: can I use a second SN65LVPE502A? I read the answer in another thread with a similar question, where it was advised to use a TUSB522P. The point is that I need extended temperature devices (-40/+85°C), and presently I cannot find any TUSB522PI from standard suppliers (Digikey, Mouser, Avnet).

Thanks for help.

  • 0
    TI__Mastermind 23815 points

    Hi Luca,

    Having redrivers in cascade make sense, we have seen customers using this approach in several protocols.

    LVPE502 and LVPE512 are no longer recommended, new designs should use TUSB522P

    TUSB522PI is no yet available, it should be available at the end of March, meanwhile, you can design with TUSB522P and replace when industrial samples arrive.

    Regards

  • 0 in reply to Moises Garcia
    TI__Mastermind 23815 points
    Hi Luca,

    I forgot something important:

    LVPE501 and LVPE512 cannot be used in cascade.
    TUSB522P can be used in cascade.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 70 points

    Hello Moises,

    thank you very much for your answer. In your second post you mentioned the LVPE501 which, as far as I can see, is a PCIe redriver. Did you mean LVPE502?

    Apart from this, my concern is that I'd like to avoid the redesign of the carrier (which is already in production), where the SN65LVPE502A is hosted. But, if I understand correctly, you are saying that cascading another device after the LVPE502A won't work, regardless of the device used, is it right?

    So, just to be clear, none of the following solutions will work:

    Host --> SN65LVPE502A --> SN65LVPE502A --> Device

    Host --> SN65LVPE502A --> TUSB522PI --> Device

    Host --> SN65LVPE502A --> (TUSB501 + TUSB501) --> Device          (This could be nice, since the TUSB501 is already in production)

    and only the following ones will work:

    Host --> TUSB522PI --> TUSB522PI --> Device

    Host --> TUSB522PI --> (TUSB501 + TUSB501) --> Device

    Host --> (TUSB501 + TUSB501) --> TUSB522PI --> Device

    Host --> (TUSB501 + TUSB501) --> (TUSB501 + TUSB501) --> Device

    Is it right?

    In fact, since the TUSB522PI is pin-to-pin compatible with the SN65LVPE502A, I could think to assemble it on the carrier. This can be done, but I'm worried about waiting for the industrial version, since the end of March is a bit late for me.

    Thanks again for your help.

    Regards

    Luca

  • 0 in reply to Luca Rigazio
    TI__Mastermind 23815 points
    Hi Luca,

    The working configurations you mentioned should work fine.
    This configuration may work, but it has not been tested extensevely, you can try at your own risk.
    Host --> SN65LVPE502A --> (TUSB501 + TUSB501) --> Device

    The recomendation is the same, design with TUSB522P and wait for the industrial version to be available.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 70 points
    Ok Moises, thanks, for me the issue is closed.
    Regards
    Luca