[Arm-netbook] EOMA68 laptop battery management.

Jakub Kákona kaklik at mlab.cz
Wed Mar 2 12:15:24 GMT 2016


I take look on the bq24193's datasheet  and I think it is almost perfect IC
for intended application.
STC3115 seems to by quite cheap but not the best solution.

We currently have quite outdated, but still better battery gas gauging
design based on BQ34Z100.

Documentation is here

I think the main work should be the redesign of our LION1CELL01A module
with bq24193 charger integrated in it. We should do it in KiCAD probably in
form of new MLAB module (for testing). The exact PCB for Libre laptop
should be derived from it then.

Is current blocks/circuit schematic of Libre laptop somewhere? I do not
understand how the higher voltages (+5V) or +12 (for LCD) are efficiently
generated from battery? Has this design higher efficiency than two balanced
cells connected in series?

2016-02-28 23:54 GMT+01:00 Luke Kenneth Casson Leighton <lkcl at lkcl.net>:

> ---
>  ok, well actually there is a sub-task that i could do with your help
> on: i need a 15 watt *single-cell* battery charger / monitor board
> which is compliant with the USB-OTG Power specification up to 3A @
> 5.0V and can be controlled via I2C as to which direction the power
> goes... *and* can take DC input at the same time.  i've found the
> bq24193, it's the best i could yet find that will do the job.  the
> only thing is, its I2C interface is hard-wired to 1.8v and i need 3.0
> to 3.3v, so there will be some level-shifting needed there.  it also
> will need a battery monitor (coulomb counter) - the STC3115 QFN is
> what i had in mind, but if you have something better please do say so.
> PCB size needs to be no bigger than 32 x 85mm, 1.5mm thickness, 2
> layer *ONLY*, components *ONLY* on one side, no through-hole
> components or connectors are allowed, and there is a severe [hard]
> height limit of 5.5mm so the only DC connector i could find which can
> handle 5A and is within that limit is the PJ-018H-SMT from CUI Inc.
>  also, i really loved the solar panel idea and it turns out that the
> PJ-018H-SMT has a 3-pin arrangement, so in theory a diode and a solar
> panel in series between pins 2 and 3 would provide solar power when
> the DC-jack is disconnected.  pin 3 (to which the solar panel would be
> wired) would be disconnected when the DC jack is in.  pin 2 is GND.
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