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TUSB4020BI-Q1: Does TUSB4020 affect the OTG function of upstream USB

yang tao
Prodigy 80 points
Part Number: TUSB4020BI-Q1
Other Parts Discussed in Thread: TPD3S714-Q1, TPD3S716-Q1

Tool/software:

Dear team,

I have a question whether TUSB4020 will affect the OTG function of upstream USB,  Please help answer;

The application scenario of TUSB4020 is as follow:

  • The USB1 of SOC connects to the UP USB of TUSB4020, And the USB1 of SOC supports the OTG function.
  • The DN1 USB of TUSB4020 connects to the TPD3S714，and The connector USB of TPD3S714 will connects to PC or U-Disk.

Does the connector USB of TPD3S714 also supports OTG function?

 

  • 0
    TI__Guru**** 161366 points

    Hi,

    The TUSB4020 does not support OTG function. When connecting to a SoC that supports OTG, the SoC will always act as a host and TUSB4020 will always act as a device.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    Thank you for your answer.

    If we connect connector USB of the TPD3S714 to PC, Downloading the firmware to SOC via the connector USB of the TPD3S714, Can it be possible?

  • 0 in reply to yang tao
    TI__Guru**** 161366 points

    Hi,

    To clarify, do you mean connecting TPD3S714 to the downstream port of the hub, not the PC?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    The downstream port 1 of the hub connects to TPD3S714, and the PC connects to the VD± of the TPD3S714.

    Can a PC flash firmware to the SOC via TPD3S714?

  • 0 in reply to yang tao
    TI__Expert 6405 points

    Hello,

    TPD3S714-Q1 expects power to flow from right to left as shown in your diagram.  There is no issue with an OTG data role swap.  The D+/D- pins will let data pass regardless of host/device role.

    But there is risk if expectation is that PC will provide 5V power on VBUS.  When both PC and your system attempt to provide 5V, they will likely not be exactly equal.  This may trip the overcurrent protection and assert a fault.  TPD3S714-Q1 cannot disable the VBUS path independently of the data path.

    I recommend considering TPD3S716-Q1 instead.  It has separate enable signals for VBUS and data path.  So when you want to update the SOC, ensure VBUS path is disabled but data path is enabled when connecting the PC.  The PC can then assume the host role and provide 5V without issue.

    Regards,
    Eric