USBC

[mjordan]

I have a product powered from a iPad (the iPad is enclosed in a case, the USBC plug on the iPad is no longer accessible from the outside of the case).

Internally (of the case) I have an 8pin USBC cable from the iPads USBC port to a custom PCB. From the iPad USBC/PCB connection I wish to tap power from the iPad to power the PCB (a low current design, ~100ma)

On the custom PCB I also have a female "external USBC" which I require to charge the iPad.

D-/D+ is not being used. No data transfer, this is strictly power only application

My problem is that upon plugging in the "external USBC" into the PCB, the iPad is not charging. I believe it's because the iPad is never leaving is "source" role to become the power "consumer". I believe this is controlled with the resistors on the CC pins and I have tried to handle that, but I am missing something...

Rather than post what is not working (basically 5K1 on CC and P-Channel MOSFET with the "external USBC" VBUS on the gate)...  I was hoping someone could point me to an existing solution. I can't be the first person trying to tap power from a iPad, but then also charge the iPad without removing the iPad's existing USBC connection.

Thanks in advance for your help.

[fchk]

You will need a dual role USB-C power controller. Such as:
https://www.st.com/en/interfaces-and-transceivers/stusb1600.html
https://www.ti.com/lit/ds/symlink/tusb320lai.pdf

[mjordan]

Thanks for your reply! I've been reading up on the TUSB320 this morning. I agree this is the way to go, but I am unsure how to use it. Do you know of any references that would help me use the TUSB320 to do something like in the image?