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TPS65986: Power Negotiation in Mini-dock Coniguration

Part Number: TPS65986

Hello,

This question relates to our TPS6598x devices, particular in a system similar to our mini-dock reference design: TIDA-01243

The section of the design I am curious about is the power path from USB-C UFP (port where the board is receiving power from) to the USB-C DRP (port where the board is providing power from). I think it is easiest if I showcase two scenarios:

1. Connected to the DRP is a device requiring 5V 1A. Connected to the UFP is a Type-C compliant AC/DC power brick, capable of providing up to 60W (20V 3A).

2. Connected to the DRP is a device requiring 15V 3A. Connected to the UFP is a Type-C compliant AC/DC power brick, capable of providing up to 60W (20V 3A).

Questions:

  1. In scenario #1, what power profile will the UFP negotiate with the AC/DC Type-C brick? Will it always provide 20V since both devices are capable of a 20V connection, even though the load is only 5W?
  2. When switching from scenario #1 to #2 (when the DRP goes from sourcing 5W to 45W), does the UFP also have to renegotiate with the AC/DC Type-C brick to accommodate this much higher load?

I hope that all made sense, please ask if you need more info. Thank you!

Regards,
Ryan B.

  • Hi Ryan,

    We have to assume a little based on the design block diagram. Implementing this system requires TPS6598x firmware customization (use the Application Customization Tool to do this). We may set up the UFP Charging port with a 12-20V 5A Sink PDO set to ask for the maximum offered from the power brick. Then we would expect it to request a full 20V contract.

    The TPS6598x devices are capable of responding to GPIO events to update their Source or Sink PDO profiles based on setting from Application Customization. This design does not have an embedded controller to update device settings so it will depend on GPIO events to change power profiles if needed.

    Regards,
    Scott