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TUSB4020BI-Q1: TUSB4020BI-Q1 Battery Charging mode change

Red Yen
Expert 4360 points
Part Number: TUSB4020BI-Q1

Hi Support team 

Ask a question about USB HUB (TUSB4020BI-Q1), Battery charging mode is mentioned in Spec as follows

The TypeA Connector has a mobile phone connected, and then removes the mobile phone after entering the CDP Mode;
At this point, change the Apple mobile phone to connect to the same port. Can you enter the Divider Mode from CDP Mode?
If so, how does the USB HUB IC know about device changes?
Is it based on the mechanism to detect whether a device is connected or removed?
Or can you judge with the pin in TypeA VBUS/DM/DP/GND?

  • 0
    TI__Guru 64326 points
    Hi Red,

    We are looking into this and will get back to you shortly.
  • 0
    TI__Guru 60870 points

    Hi Red,

    Section 8.3.1 in the TUSB4020B datasheet has more information, but please be aware that if automode is enabled (Divdier Mode, DCP mode) then CDP mode is disabled.  Most of the common later generation phones are able to charge in DCP mode, so I would recommend leaving AUTOMODE disabled.

    To clarify the system behavior if battery charging is enabled and automode is disabled:

    If the upstream port of the hub is connected to a host, the downstream ports are powered on and can support CDP charging (power+data)

    Once the upstream port of the hub is disconnected or the host is powered off, the downstream port power is briefly toggled low and then the downstream ports enter DCP mode (power only).

    When the upstream port of the hub is reconnected or the host is powered on, the downstream port power is briefly toggled low again and then the downstream ports enter CDP mode (power+data)

    Let me know if you have any additional questions.

    Regards,

    JMMN