[Arm-netbook] Laptop Housing Questions

[mike.valk at gmail.com]

2016-12-19 22:56 GMT+01:00 Luke Kenneth Casson Leighton <lkcl at lkcl.net>:

> ---
> crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
>
>
> On Mon, Dec 19, 2016 at 9:45 PM, Jonathan Frederickson
> <silverskullpsu at gmail.com> wrote:
> > Hey, I have a few questions about the laptop housing.
> >
> > - How does one connect it to power?
>
>  standard DC jack, anywhere between 7 and 19v.
>

I've never found a standard DC jack ;-). I presume a "dognut" type plug? If
so, of what dimensions and which polarity or does it have a polarity
switcher or at least a polarity safety?

I think the USB-C connector is going to be the first "standard" "universal"
charging connector. Standard USB-C cable should be able to provide 60W
(20V*3A) and power cables 100W (20V*5A). But not "ominous" enough yet.


> > Can it be powered over USB
>
>  powered no, charged, yes.  current limit on the OTG port.
>

Well if the input minimum is 7V than neither.

But if I understood correctly the EOMA-68 card accepts power over the OTG
port and passes through, any surplus, to the housing. Thus slowing down the
battery drainage of the housing(laptop/tablet). And charging, although
slow, when the housing is turned off. And a little faster when both,
housing and card, are turned off.

Standard USB only delivers 5V*500mA= 2.5W. But various options are allowed
apparently. https://en.wikipedia.org/wiki/USB#Power


>
> >  or does
> > it require a specific AC adapter?
>
>  no.  min 4A is best, but if you're prepared to reprogram the
> STM32F072 yourself you could get away with less
>

4A on the output side I presume so 19v*4A=76W, So a 95W power supply with
80% efficiency (90*80%=76). Or 85W at 90%.


>
> > I have a portable solar array with a
> > battery pack that can charge portable devices over USB, and I'm trying
> > to work out whether or not I'll be able to power the laptop from it.
>

If it has 12v out that would be your best bet I guess.
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