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TPS65987D: device response to 5V charger with no PD negotiation

Don Foong
Expert 4100 points
Part Number: TPS65987D

Hi Team,

One of our customer is using TPS65987D for their product design for power sink only + USB2.0 connection only (no Alternate Mode, no USB-3/SS link). Before adepter plug-in, TPS65987D is not power by the VIN_3V3. It is arrange to be powered from the 3.3V LDO when VBUS became available. Attached is the PD controller pjt file and the schematic for reference.

Customer hope to understand what is the expected behavior from the TPS65987D when a 5V(3A) charger (no PD negotiation) is connected. Can you help to provide your comments for below two use cases, thanks in advance.

1. a charger which advertises its current capability only via the Rp pull up resistor on the USB-C CC1 and CC2 lines.
2. a charger which does not advertise its current, just presents 5V on the Vbus line.

Thanks and regards,

Don

TPS65987DDH_file.pjt

  • 0
    TI__Mastermind 27535 points

    Hi Don,

    When a source is attached to the Type-C port and the TPS65987D does not have power on VIN_3V3, we refer to this as a dead battery scenario. In this scenario, the TPS65987D presents an Rd on the CC lines in the event that a source presenting an Rp is attached, allowing for the system to still power up. An example of this use case is with a laptop that has a USB Type-C PD port capable of charging from. If the battery is completely drained, there will be no voltage present on VIN_3V3. However, a customer would still expect their laptop to charge, so the TPS65987D presents the dead battery Rd to negotiate an implicit contract. 

    Let me know if this helps answer your question 

  • +1
    TI__Expert 4100 points

    Hi Mcgaffin,

    Thanks for the feedback.

    You have answered the questions. Thanks again for the support.

    Regards,

    Don