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TPS65982: Re-negotiation on subsequent plug-ins

Alex Summer
Prodigy 40 points
Part Number: TPS65982

Hi, we are using the TPS65982 for our PD charger application (sink power delivery from type C port).   On initial power up with 20V external plugged in from the type C port, the battery charges as expected, when the external power is removed, the battery power kicks in to supply system power, however, once the external power is plugged back in a few seconds later,  the PD controller is unable to renegotiate.  We are assuming the negotiation is done automatically.  As a side note, the VDDIO and VIN_3V3 are connected to an on-board 3.3V supply instead of using the controller's LDO_3V3.  Would this impact the behavior we are seeing?

We'll try to repeat this using the EVM board, but in the meantime, would connecting VDDIO and VIn3v3 this way cause the issue we are seeing? 

Thanks.

  • 0
    TI__Expert 6430 points
    Hi Alex,

    I don't this VDDIO and VIN_3V3 is the issue. We think the issue is your system has no way to know that the 20V external power supply was connected. Are you using Barrel Jack event in your design?

    This event will ensure that power is renegotiated when an external supply is connected.

    Thanks,
    Rahul
  • 0 in reply to Rahul Sharma16
    Prodigy 40 points

    Hi Rahul,
    No barrel jack is used in the design. An external AC/DC supply provides the 20V and comes thru the Vbus pins of the USB type C connector on our board. Our design is based on the reference design and utilizes the external power path configuration. We noticed that when re-plugging in the type C cable, the HV_GATE[1:2] pins output 5V, and effectively do not turn on the back-to-back external N-CH Fets. When no battery is connected in present in our system, power negotiation is fine when plugging and unplugging the external power cable multiple times.
    We'll also verify the state of "GPIO1, DEBUG[3:4], GPIO5" are properly boot-strapped to configure the device as "High-Power Bus-Powered Device".

    [Update] 11-28.  We confirmed that the settings for the GPIO and DEBUG[3:4] inputs were incorrect, and thus putting the PD controller in a mode other than High-Power Bus-Powered Device.  Once they are correctly set to 1110, then the original issue went away, and transition from battery to 20V works as expected.