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TPS25831-Q1: About resistance value of CC1 and CC2 at Enable is OFF

Hide
Guru 21045 points
Part Number: TPS25831-Q1

Hi Team,

 

I have two questions.

 

-------

[Q1]

I would like to know the actual resistance value between CCx(CC1/2) and GND.

Could you please let us know if you have any information?

 

[Q2]

If the TPS25831-Q1 is turned off with the DRP device connected,

there is a phenomenon that power is supplied from DRP device, which was UFP.

Is it possible for DRP device to unintentionally switch from UFP to DFP?

 

I guess that DRP device violates the Type-C standard, but is it possible that TPS25831-Q1 is the cause?

-------

 

Regards,

Hide

  • 0
    TI__Mastermind 18556 points

    Hi Hide,

    I will reply to you later.

    Best Regards,

    Kuno

  • +1
    TI__Mastermind 18556 points

    Hi Hide,

    1.Sorry, I have no information about this, but it should be ‘High Resistance’.

    2.The TPS25831-Q1 can only do 'Source', so it will not the reason for this issue.

    Best Regards,

    Kuno

  • 0 in reply to Kuno Wu
    Guru 21045 points

    Hi Kuno-san,

    Thank you for the information.

    Regards,

    Hide

  • 0 in reply to Hide
    TI__Mastermind 18556 points

    Hi Hide-san,

    You are welcome.

    Best Regards，

    Kuno

  • 0 in reply to Kuno Wu
    Guru 21045 points

    Hi Kuno-san,

     

    I have one question.

    I would like to know “High Resistance” of your comment.

    Is this resistance value more than 1Mohm?

    So, is it sufficiently larger than the Rds=5.1kohm specified in the Type-C standard?

    (Actual resistance value between CCx(CC1/2) and GND >> Rds=5.1kohm)

     

    <Background>

    I understand that TPS25831-Q1 can support source(DFP) only(can't supprt sink(UFP)).

    However, I am worried that TPS25831-Q1 will be unintentionally recognized as UFP.

     

    Regards,

    Hide

  • 0 in reply to Hide
    TI__Mastermind 18556 points

    Hi Hide-san,

    Sorry, I misunderstand what your mean, I mean the 'High resistance' is based on you float the CC pin, because you said that you turn off the device, so I think you float the CC pin. And the TPS25831-Q1 can not support UFP from my side.

    Best Regards,

    Kuno

  • 0 in reply to Kuno Wu
    Guru 21045 points

    Hi Kuno-san,

    Thank you for your prompt reply.

    I understand that TPS25831-Q1 can’t support sink(UFP).

     

    Could you please let us know actual resistance value between CCx(CC1/2) and GND?

    No explicit value is needed (for example, more than 1Mohm etc.).

    I would like to know whether it is sufficiently larger than the Rds=5.1kohm specified in the Type-C standard.

     

    Regards,

    Hide

  • 0 in reply to Hide
    TI__Mastermind 18556 points

    Hi Hide-san,

    Actually we use a current source in the CC pin, when you attach a Rd or Ra in this pin, it will through the resistance to set up a voltage, then our device will detect this voltage to know what is the resistance value to attach, so when you float the CC pin. the theoretical resistance must be infinite, more than 1Mohm.

    Best Regards,

    Kuno

  • 0 in reply to Kuno Wu
    Guru 21045 points

    Hi Kuno-san,

     

    I have one more question.

     

    I guess that if device is disable(Power is not supplied), internal a current source is disable.

    Then, theoretical resistance of CC pins are infinite.

    (so it is similar to the state of "float the CC pin".

    Is my understanding correct?

     

    Regards,

    Hide

  • 0 in reply to Hide
    TI__Mastermind 18556 points

    Hi Hide-san,

    In this time, whether you connect a Rd or Ra to CC pin or not ? If you do not connect any resistance in the CC pin, yes, it is the same as 'float', if not, I think you can not think it is 'float'.

    Best Regards,

    Kuno

  • 0 in reply to Kuno Wu
    Guru 21045 points

    Hi Kuno-san,

     

    Let me correct the information a little.

    DRP device have Rp and Rd so either will be connected.

     

    I guess that if device is disable, internal a current source is disable.

    Then, theoretical resistance of CC pins are infinite.

    Is my understanding correct?

     

    If yes, I guess that even if the resistance on the DRP device side is RP or RD, there will be a high resistance.

    Is my understanding correct?

     

    <My image>

     

     

    Regards,

    Hide

  • +1 in reply to Hide
    TI__Mastermind 18556 points

    Hi Hide-san,

    Yes, your understanding is correct.

    Best Regards,

    Kuno

  • 0 in reply to Kuno Wu
    Guru 21045 points

    Hi Kuno-san,

    Thank you for kind support.

    Regards,

    Hide