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TPS65987EVM: Can the 5V sink be disabled

Elad Eshkol
Prodigy 130 points

Part Number: TPS65987EVM

Hi, i am trying to disable the use of 5V when the PD in in SINK mode.

is it possible to set up this PD controller to sink only 9V,12V,15V,20V  but not 5V ?

the problem we i am having is that when i connect my system to a laptop, it tries to pull more than 1A from the USB port, but i only want to have the USB data lines in this case.

when charging i will use 12V/20V charger.

is it possible and if yes how ?

Thank you  

  • 0
    TI__Mastermind 27665 points

    Hi Elad,

    If you have a external EC present, you could use the 4cc command 'SRDY' which would only close the power path once this command has been received. You would update the configuration of the power path 0x27 to "PP2 configured for Sink (input), but will wait for SYS_RDY command (SRDY) before closing the switch". You would read the updated register about the sink capabilities and then send this command once the negotiated contract is >5V

    However, if you do not have an EC present to issue this command, then you will have to first negotiate the 5V contract before transitioning to 12V

  • 0 in reply to Adam Mc Gaffin
    Prodigy 130 points

    I have a mcu in my design, and i understand your answer.

    but is there no way to disable 5V from usin more than 1A, or that the PD will not negotiate 5V at all ?

    i think that if i need the mcu communication to have this, this means no bead battery charging option.

    thank you 

  • 0 in reply to Elad Eshkol
    TI__Mastermind 27665 points

    Hi Elad,

    No there is no way to disable not negotiating 5V at all. With the 'SRDY' solution, the PD controller would still negotiate 5V, but the power path would not close until a larger voltage has been applied to VBUS.

    You would still have dead battery, it would just negotiate 5V first depending on the default configuration you have it set to.

  • 0 in reply to Adam Mc Gaffin
    Prodigy 130 points

    Hi Adam, thank you fir you replay

    I have tried using the 'SRDY' solution on the dev kit, what i see is that 5V still shows on the output of the board right away.

    what i might be missing ?

    thank you

    Elad 

  • 0 in reply to Elad Eshkol
    TI__Mastermind 27665 points

    Hi Elad,

    A 5V contract will still be negotiated and presented on VBUS, however the power path will not close until the SRDY command is sent. So the system will not see the voltage on VBUS until this command is sent and the power path is closed.