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TPS65987D: Dual power role and BC 1.2

martin bugge
Prodigy 180 points
Part Number: TPS65987D

Hi.

This is maybe more of a general USB-C question.

We have a USB-C port design with TPS65987D which primarily is meant for connecting laptops.

It can via Power Delivery supply power at 5, 9, 15, 20V all at 3A.

USB Datarole is UFP, providing USB devices for webcam and audio.

Receive video from DP UFP via Displayport alternate mode.

And we are Dual Power role such that you can connect your PC with an USB-A to USB-C cable and still get the USB devices.
(But no DP video then).

However, since we are Dual Power role you can also connect with a USB-C to micro cable.

Can we enable Battery Charging BC 1.2 to effectively become a Dedicated Charging Port ?

Will the TPS65987D keep track of the Power and Data role states and handle the USB2.0 lines accordingly ?

And is it recommended to have BC in such a design ?

Thanks in advance,

Martin Bugge

  • 0
    TI__Expert 4795 points

    Hi Martin,

    Yes our TPS65987D handles BC1.2 detection and advertisement and connects directly to D+/D- pins to handle that communication. You can find BC1.2 details in our datasheet as well as our design guide here:

    https://www.ti.com/lit/an/slvae17a/slvae17a.pdf?ts=1717063492261&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS65988

    Let me know if that answers your question. It's not entirely clear to me what exactly your end equipment application is doing or needs from the PD controller, so if you can provide more details or block diagram that will be helpful.

    Thanks,

    Matt

  • +1 in reply to Matthew Schafer
    Prodigy 180 points

    Thank you Matt.

    From you document:

    "The charging advertisement mode is entered only when the port is connected as source. The charging
    detection mode is entered only when the port is connected as sink. The port needs to enter Type-C
    connection state of Attached.SRC or Attached.SNK to advertise or detect BC1.2 mode"

    So if I understand this correctly it should be safe to enable BC1.2 charging even if we are dual power role.
    (CC lines are toggling between pull-up/down).
    The TPS65987D controller will handle this and only advertise BC1.2 when attached as source.

    Martin