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Original question:

TUSB4041I schematic

TUSB4041I: Basic implementation of the HUB

William Delacre
Prodigy 20 points
Part Number: TUSB4041I

Hi all !

I would like to use the TUSB4041I as a simple classical USB HUB (no battery charging)

I found this thread which is basically what I’m trying to do but there are 2 things I don’t understand :

1) In the comments it’s said that the FULLPWRMGMT pin should be tied high, but from the schematics uploaded in the thread it seems to me that it’s already the case...

2) what’s the purpose of the voltage divider bridges on pins 13, 8 and 10?

It’s not possible to connect them directly to a VDD33 source ?

Thanks in advance !

  • 0
    TI__Guru 60870 points
    Hi William,

    1. The customer put both pullup and pulldown options on the configuration pins. It looks like the responder just wanted to clarify that they needed to implement the pullup option on FULLPWRMGMTz pin.
    2. Those should not be voltage dividers, they should be pullup or pulldown pop options - only one should be installed on each line.

    That schematic was generated by a customer, not TI. Functionally, it is fine but it should be noted that USB specification requires overcurrent reporting if you are implementing a design that will be considered for USB -IF logo.

    The EVM users guide has a TI design in it: www.ti.com/.../technicaldocuments

    Regards,
    JMMN
  • 0 in reply to JMMN
    Prodigy 20 points
    Oh yes with the pull-up / pull-down choice it makes sense ! Thanks for the clarification !

    The downstream USB devices that will be connected to the HUB won’t get plugged/unplugged but physically wired to the HUB so I don’t really need overcurrent protection, right ?

    And yes, to design my circuit I mostly used the HUB official documentation and given examples !

    To be sure : as I don’t need any battery charging option, FULLPWRMGMT and AUTOEN pins can be tied high, right ?
    What about GANGED and PWRCTL_POL pins ?
    I don’t really understand the related section in the Datasheet...

    Thanks again !
  • 0 in reply to William Delacre
    TI__Guru 60870 points
    If you have permanently connected devices, overcurrent reporting isn't required but marking the ports as non-removable via EEPROM or SMBUS is required for USB-IF compliance. Again, functionally this is not a requirement - the hub works the same either way.

    Yes, FULLPWRMGMTz should be pulled high. AUTOENz, GANGED, PWRCTL_POL are don't cares for your application. I would recommend using the internal pu / pd defaults instead of external ones on these pins. Several of these pins become status outputs during normal operation and using external pu / pds can increase power consumption.

    Regards,
    JMMN