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TPS65987EVM: Overcurrent Clamp Setting

K.Yaita
Guru 29720 points

Part Number: TPS65987EVM

Hi Team,

I have TPS65987EVM and confirmed Overcurrent Clamp feature by changing Maximum Current in Transmit Source Capabilities (0x32).



The actual trip point of Overcurrent Clamp is the following and the result is the same under Maximum Current is ~0.3A.
Is the result reasonable for TPS65987D?



I would also like to know if it is posible to set trip point to ~0.44A. (for example 0.1A etc)

Best Regards,
Yaita

  • 0
    TI__Mastermind 30000 points

    Hello Yaita,

    We do not recommend using current clamp settings that are not listed within the datasheet (shown below). How our device works is that based on the current limit set within the firmware, it will choose the closest option within the table listed. There are three more current settings that go below the 1.14A limit, one of them being the 0.44A limit you are seeing, but these are unreliable and we do not recommend using them.

    As far as setting a maximum current of 50mA, I do not see the practicality in something like this. Typically, as Type-C charging port must supply at least 500mA and 900mA of current for legacy USB2.0 and USB3.0 charging devices.

    Hope this helps answer your question. If so,  please click THIS RESOLVED MY ISSUE

  • 0 in reply to Adam Mc Gaffin
    Guru 29720 points

    Hi Adam-san,

    Thank you for your support.
    The background of the requirement is my customer wants to change sorce power dynamically.
    The detail is posted as the following link.
    -----------------------------------------------
    https://e2e.ti.com/support/interface/f/138/p/780205/2901828#2901828

    1) Consumer device is connected to the system (TPS65987D) through Type-C cable.
    2) TPS65987D provides power to consumer device depending on PD communication (ex. 15V/3A).
    3) CPU advertises TPS65987D to reduce power.
    4) TPS65987D reduces power provoided to consumer device (ex. 15V/3A -> 5V/0.1A).
    -----------------------------------------------

    Do you refer the following 1.267A(typ) is the smallest current that should be set? 
    My customer wants to reduce power provoided to consumer device as small as possible.



    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Mastermind 30000 points
    Hello Yaita,

    Yes, I recommend that 1.267A(typ) is the smallest current that should be set. Anything below this threshold will not have guaranteed current limit values, and could lead to adverse conditions.
  • 0 in reply to Adam Mc Gaffin
    Guru 29720 points

    Hi Adam-san,

    Thank you for your continuous support.
    I understand 1.267A(typ) is the smallest current that should be set for Maximum Current field of "Transmit Source Capabilities (0x32)".
    Is there another way (hardware OCP, firmware OCP, etc) to set current limit less than 1.267A(typ) for TPS65987D?

    If the answer is no, I should suggest external current limit switch to meet my customer's requirement..

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Mastermind 30000 points
    Hello Yaita-san,

    Unfortunately no, there is no other reliable method to set the current limit less than 1.267(typ) using the TPS65987D. If your customer has a firm requirement to set the current less than this, would recommend using and external current limit like you suggested. Best of luck with your design.