[Arm-netbook] EOMA68 laptop battery management.

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Mar 2 18:20:22 GMT 2016

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

On Wed, Mar 2, 2016 at 4:48 PM, Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:
> On Wed, Mar 2, 2016 at 4:25 PM, Jakub Kákona <kaklik at mlab.cz> wrote:

>>  But a
>> current design is still not fully clear to me.

 ok i've created a diagram, it's basically identical to the current
PCB3 schematic, except LTC4155 is replaced by a combination of bq24193
plus txs0104 plus 1.8v regulator, and STC3115 is replace by BQ34Z100.


 key differences from what you *might* be expecting this Charger PCB to have:

 1) there is NO 5V rail.
 2) there is NO 12V rail
 3 ) there is NO 3.3v rail
 4) the (appx) 4.2V "SYS" voltage from the Charger IC goes straight out *as-is*
 5) Digital GPIO requires a REF voltage to be safe and meaningful.
     this *has* to be EXTERNALLY SUPPLIED.
 6) many devices are now USB-OTG compliant (2-way power),
    so that is a power output (***AND POWER INPUT***)

 from what you wrote, you *may* have considered that something like
this would be useful:

 1) 5V DC output
 2) 12V DC output
 3) 3.3v output
 4) DC charging input

such a board is not useful for this project, because such a design is
for a standard laptop.  this isn't a standard laptop, it's a
USB-OTG-powered "embedded" device.


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