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PCM2704C: PSEL/HOST configuration

Yuto Kitamura
Expert 6605 points
Part Number: PCM2704C

Tool/software:

Dear team,

Would I know what I have to configure PSEL and HOST-pin?

This time system works as self-powered, thus PSEL should be low.

How about HOST-pin? this system only support 5V/3A with power source but it is PD controller, it may be input 20V or something. So I am not sure we can connect it to VBUS. Or can we connect to 5V or 3.3V?

System:

- TPS25751SRSMR
- Power: 5V/3A source only
- Data: Device only with USB2.0
- Self powered
Use role swap to achieve Power source and Data Device by PD controller.

Best regards,
Yuto Kitamura

  • 0
    TI__Mastermind 46625 points

    Hi Kitamura-san,

    These devices are not intended for USB-PD since they were designed only for USB 2.0 and 1.0. You cannot connect Vbus to any 5V/3.3V supply since the HOST pin must be pulled up to Vbus. I would recommend the PD control keep the Vbus at 5V instead of 20V since the codec cannot support it. 

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    TI__Expert 6605 points

    Hi Jeff,

    Thanks for comments.

    In terms of the IC operation, how will it be when HOST leaves float or keep GND when self-powered mode? In other words, how will it be if it cannot detect Vbus attach and detach.

    According to the D/S page#20, it must be connected to Vbus as you mentioned.

    But according to the page#35, HOST must be "high", but not Vbus. If so, it can be tied to Logic high. If it would be the work around, it can help to avoid from unexpected OV externally or "PD device."

    Best regards,
    YK

  • 0 in reply to Yuto Kitamura
    TI__Mastermind 46625 points

    Hi Kitamura-san,

    In the application diagram you shared HOST is still tied to VBUS directly. 3 is referencing D+, not HOST. 

    While it might be possible that it still works with HOST tied to logic high, I am not sure of the side-effects. USB is a well-defined protocol and I worry that there might be a communication error if HOST is high without a connection to USB.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    TI__Expert 6605 points

    Hi Jeff,

    Thanks for clarification. I recommended to tie host to VBUS to the customer.

    Best regards,
    Yuto