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TPS65987D: Issue with power delivery at 5V

Collin K
Prodigy 10 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TIDA-050012, USB-C-PD-DUO-EVM, , TIDA-050014

Hi,

I am currently in the process of developing a product which will incorporate a USB-C / USB Power Delivery Source and am using the TPS65987D as the Type-C/Power Delivery controller.  The design uses the TIDA-050012 Source Board reference design as a general guide for implementation.  I also have the USB-C-PD-DUO-EVM as a reference and to use as a USB-C PD sink to test our product. 

The issue I am having is when the source/sink negotiate 5V voltage level, it is not possible to place more than ~1.2A load on the sink output before some sort of protection mode kicks in, disconnecting the USB_VBUS.  After this happens, PD negotiation restarts, and the sink powers back up.  I explored the documentation and settings in the TPS6598x Application Customization Tool, and changed a few things that seemed like they might matter (undervoltage trip point, etc) with no effect.  The other voltages (9V, 15V, 20V) operate to our full current requirement (3A) without issue.  The power supply used in our design can deliver 0-3.5A at 5V and all the other voltage settings.  A DC electronic load is being used as the load for the sink.

When I do this same test using the Evaluation Source and Sink board, with the default configuration loaded from the Application Customization Tool, the behavior is exactly the same (restart at 5V/~1.2A, works ok on other voltage settings).  I tried a few different manufacturer's USB-C cables between source and sink but there was no change.

Do you know why I can't reach the full 5V/3A, even with the eval module?  Apologies in advance if I am missing an obvious answer for this in the documentation or on this forum.

-Collin

  • 0
    TI__Expert 6280 points

    Hi Collin, 

    Can you confirm that you have the Type-C and PD current setting at 3A? 

    Probing VBUS and the PPHV input during the testing will let you know if the PD controller OCP protection is kicking in. If the PPHV voltage falls with the VBUS voltage then the DC/DC converter is the issue. If PPHV stays constant and VBUS falls then the PD controller is hitting some type of protection. 

    Jacob

  • 0 in reply to Jacob Ontiveros
    Prodigy 10 points

    Hi Jacob,

    I confirmed that the Type-C Current and PD Maximum current are both 3A.  When the fault occurs, Vbus falls while PPHV remains constant, so some sort of protection is being triggered by the PD controller.  This behavior is the same for our hardware as well as the development board.

    Thanks,

    Collin

  • 0 in reply to Collin K
    TI__Expert 6280 points

    Hi Collin,

    Could you share your project file?

    If the PD Contract in place is set to 1.5A the current limit setting on the PPHV path would be 1.5A. Do you have a PD analyzer handy?

    Jacob

  • 0 in reply to Jacob Ontiveros
    Prodigy 10 points

    Hi Jacob,

    Apologies for the delayed response.  The root cause of this issue turned out to be on the Sink board, the TIDA-050014 configuration for Transmit Sink Capabilities has a default of only 0.9A for the Minimum Operating Current request for 5V, and it seems like a value near to this was being negotiated, leading to the original problem.  Changing this to 3A resolved the issue.

    Thanks for your help!