On Sun, Feb 26, 2017 at 12:04 PM, Internet
<internet@devpi.de> wrote:
Yeah, that is true. But the one on PCB1 only cuts power for the USB A ports.
ah! then i'm thinking of the microdesktop, and haven't looked at PCB1 recently enough to remember that. i have a vague recollection of deciding to move bidirection power-provision to PCB3.
It does not act as power switch for the card to provide charging capability. To do that you need two of them on PCB3. One has 5v from the battery as input and the 5v ports of the eoma68 card as output, the other one has the 5v ports from the card as input and the output should be wired to the input of the usb otg charger ic (through a diode otherwise 12v would damage the card). If a usb otg cable is plugged in and the computing card switches the two complementary sy6280, power would go into the usb charger ic and charge the battery which also powers the rest of the system. Power from the system to the computing card would be off because the switch is open.
However, it won't charge from the card, if the 12v adapter is plugged in (because of the protection diode).
I will clarify this on the pcbs page but at the moment I don't have access to a PC.
honestly... it would be best done as a diagram, even if it's hand-drawn and then photographed.
i recall tracking down the LT4155 (and then the bq24193 as its replacement) precisely so that external components such as the SY6280's and extra protection diodes *wouldn't be needed*. grrr :)
i _would_ suggest using the AXP209 or something else from X-Powers but i don't believe they can handle this much current (4 to 5 Amps) - certainly the AXP209 can only handle around 2A.
*sigh*...
l.
