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TUSB422: USB Hub Charge-Through port role swap to PC DRD/DRP

Bart Schade
Prodigy 10 points
Part Number: TUSB422
Other Parts Discussed in Thread: TUSB8044A, TPS25750

Can the TUSB422 - USB PD TCPCi Port Controller support a charge-through port?
And, can that charge-through port be a DRP/DRD port?


The use case is:

A special-purpose USB hub with three ports:
Hub Port 1 is dedicated to a modern smartphone (DRD/DRP)
Hub port 2 is dedicated to a custom 'power only' peripheral device (DFP) 
Hub port 3 is for either:
- a USB charger, or
- a PC for bidirectional files transfer.  

  • 0
    TI__Guru 64326 points

    Hi,

    TUSB422 is only a PD PHY controlled by the MCU and does not have a integrated power path. MCU PD stack will need to account of all the special cases and control power tree. The PD stack provided does not natively support this kind of application. 

  • 0 in reply to Malik Barton57
    Prodigy 10 points

    Hi Malik,
    Thanks, I'm getting started with a redesign and investigating ways to solve this problem.

    When you look at the diagrams I sent, can you make a recommendation how to solve the use case #3 when a user unplugs the USB charger (in charge through mode) and  connects a PC? 

    I have been studying the specs and can not find a definitive statement that this role swap (from charge through port to DRP) is NOT supported.

    Bart

  • 0 in reply to Bart Schade
    TI__Guru 64326 points

    Hi Bart,

    If the charge through port is still in DRP/DRD mode I do not see a issue. Both PC and Charger would act as DFP only (typically) with the charging having no data. The Charge through you mention is not defined by the USB spec for hub/dock type systems. Are you planning to power this design form VCONN only? creating a CTVPD would have these kinds of charge through considerations. Are you using battery in this application?   

  • 0 in reply to Malik Barton57
    Prodigy 10 points

    Hi Malik,

    I dont think VCONN can be used.  There is no captive cable in the hub, as I illustrate.  I understand a captive cable supports only charging.  I sthat correct?

  • 0 in reply to Bart Schade
    Prodigy 10 points

    Hi Malik,   
    Let me try to make this inquiry simpler to answer.  I need to design a hub that does what is described in the following two slides.  
    What TI components and reference designs should I review that can be used to support this functional requirements?

  • 0 in reply to Bart Schade
    TI__Guru 64326 points

    Hi Bart,

    To my knowledge we do not have any reference designs that are close to what you are looking for. From your description, I can say we do have a USB Hubs that can be used here however these hubs do not support DRD. This means the PC connection will always be UFP and smart phone/USB device connection will always be DFP. You should be able to achieve bi-directional file transfer if the hub connects like this. The device to use here would be TUSB8044A. 

    Power role swap messaging will allow you be flexible on which port is sourcing power and sinking power. I do not this TUSB422 is a good fit here as this application is not close to the provided source code and would require SW work. From your description it seems like our standalone PD controller would be a better fit (ex. https://www.ti.com/product/TPS25750). I am not a expert on these products (I support the data side of things expect for TUSB422) so I recommend posting another thread using TPS25750 part number to get a more accurate part recommendations.