[Arm-netbook] Laptop PCB schematics

[Luke Kenneth Casson Leighton]

---
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

On Sun, Feb 26, 2017 at 12:04 PM, Internet <internet at 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.
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