I have found an interesting looking solution for USB C on the internet. This is from a datasheet of a USB C Power Delivery controller and should also be useful for the laptop because current be transferred in two different directions as well. The setup uses different MOSFETS for controlling the current and has the ability to route it to a different location depending on the current direction. However, you still need a switch (in this case two but they are complementary). Additionally, you could use this to charge the battery and separate it from the rest of the system, if power is incoming from the card, and if the card needs power, you can simply switch it to the 5v system which should be constantly connected to the battery (boost converter).
You can find it on page 20 in the top left corner in this (http://www.cypress.com/file/140976/download) datasheet.
Julius Lehmann
On Wed, Feb 22, 2017 at 6:35 PM, Internet <internet@devpi.de> wrote:
The power issue is pretty tough I think. Do you want to allow charging from both sides (12v dc jack and eoma-5v0)
yes.or does the power from the card only act as additional power for the system (without charging and just taking the load off the battery)?
no. an OTG cable into the EOMA68 Card should be capable of charging (not necessarily *running* the system as it's far too much current required).How do you want to control the power switch (SY6280) and detect whether the card is passive or active (taking power/providing power)?
usual OTG software detection, then communicated (quickly) to avoid any current bun-fights. OTG generates IRQs from the cable being plugged in (usual way) - the extra bit will be to ensure that the required GPIOs are pulled high/low - there's quite a few.
l.
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