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TPS65987D: variable sink pdo causes windows warning message

Simon Holman
Prodigy 20 points
Part Number: TPS65987D

Hello,

we have a TPS65987D configured with 2 sink PDOs with the following:

  1. Fixed Sink: 5V / 0.5-3A  (ask for max)
  2. Variable Sink: 5-20V / 0.5-3A (ask for max)

Our product has an external supply and a battery the USB-C power is only used to supplement the other power sources, so we want accept whatever the maximum is the source can provide.

Everything works as expected, pdo are negotiated correctly, however whenever we connect to a laptop USB-C port with PD, windows gives the warning

"Your PC might not provide enough power to the USB device. Please connect your device to external power, or try using a different PC."

https://support.microsoft.com/en-us/windows/fix-usb-c-problems-in-windows-f4e0e529-74f5-cdae-3194-43743f30eed2#bkmk_usbpower_11

The laptop USB-C ports negotiate 5V / 3A (15W) and our system only requires 7.5W, but still this warning comes.

When the 2nd PDO is removed, so, only the fixed sink pdo is configured, then no warning message occurs when connected.

I've tried various pdo configurations, however whenever there is a pdo configured with more than 5V this windows warning is triggered when connected.

How should the sink pdo's be configured to prevent windows from generating this message?

I have been unable to find any documentation to explain why this message is generated.

Thanks

Simon Holman

  • 0
    TI__Mastermind 34816 points

    Hi Simon,

    Can you obtain a PD log when the windows give the warning?

    Thanks and Regards,

    Raymond Lin

  • 0
    TI__Mastermind 34816 points

    Hi Simon,

    I recommend checking the PD logs for your case, also take a look at how much power can the laptop provide from its port(s). 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Prodigy 20 points

    Hi Raymond,

    I am now able to log the PD messages.

    The port I am testing with on the Laptop can support 15W (5V/3A).
    From the logs I can see that 15W is being negotiated correctly.

    Also the data from both logs is identical, when I get the warning or not.

    It seems to only be dependent on if a 2nd PDO is configured.

    TPS config that generates warning.

    TPS config that does NOT generate warning.

    However obviously in this case only 15W  can be connected.

    We can support up to 60W.

    I also don't understand how Windows know that our device can support more power if available as the information doesn't seem to be in the PD logs.

    We also get exactly the same issue when using the USB-C-PD-DUO-EVM sink board and anything other that the 5V is selected.

    Is there a way to avoid this windows warning?

  • 0 in reply to Simon Holman
    TI__Mastermind 37855 points

    Hi Simon,

    We did some testing on our end and think the issue is related to the autonegotiate sink settings.

    Simon Holman said:
    I also don't understand how Windows know that our device can support more power if available as the information doesn't seem to be in the PD logs.

    Within the REQUEST message, the Capability mismatch bit can be toggled to let the source know if the sink is able to obtain the required power from the source. Windows most likely reads this bit and generates the "Your PC might not provide enough power" message when it is high.

    What this indicates is that the sink is expecting some minimum wattage to be supplied and the available source PDOs are not capable of providing that minimum. (i.e.. The PD auto generates a 60W (20V3A) minimum but the notebook can only provide 15W(5V3A))

    To fix this, you should only need to manually set the required power.

    Within the GUI, navigate to the Port Settings -> Autonegotiate Sink.

    At the bottom, you should be able to adjust the Power Settings. Uncheck the Auto Compute Sink Min Power to prevent the device from automatically setting the Min Required Power based on the programmed sink PDOs. Then you can set the Min Required Power manually to 7.5W (or whatever you desire) in the box below.

    Let us know if this fixes your issue!

    Thanks and Regards,

    Chris Lim

  • 0 in reply to Christopher Lim1
    Prodigy 20 points

    Hi Chris,

    Thank you, once I found the settings in the advanced configuration I was able to change it and it solved our issue.

    Cheers

    Simon

  • 0 in reply to Simon Holman
    TI__Mastermind 37855 points

    Great, Glad we were able to help!