I added the suggested schematic to 
http://rhombus-tech.net/community_ideas/laptop_15in/pcbs/ . A document from TI 
about routing power with load switches suggested basically the same except they 
used their own ics of course.

Hope this helps.

Julius

26. Februar 2017 13:13, "Luke Kenneth Casson Leighton"  schrieb:
---
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68 
(https://www.crowdsupply.com/eoma68)  
On Sun, Feb 26, 2017 at 12:04 PM, Internet  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.
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