> I've been looking around, and it seems that Sparkfun has chosen the
> Microchip MCP73831
> (http://ww1.microchip.com/downloads/en/DeviceDoc/21984e.pdf) for their
> LiPo chargers. Seems ok to me, though I'm not an expert. It does lack
> the high/low setting that was on the MAX1811 that allowed me to start
> with a lower charge rate, then crank it up when I got approval from
> the USB host.

Short

You can probably change charge rate as desired by changing Rprog
during charging.
You can probably set end current% cutoff by altering RProg once in
current taper mode.

__________________

Lonnnng

It seems capable of charge rate changes.
The resistor from PROG to Vss sets the charge rate.
It seems that altering this on the fly will alter the rate.
Resistors <=3D 2k seem to set to max mode. A diode and resistor and
digital drive should suffice.
See bottom of page 3.

If using this part get the MCPX7832-2.
The  -3 -4 -5 will cause death and destruction, possibly. YMMV.
Datasheet middle of page 1.

The IC has current taper % reduction threshold selection BUT the data
sheet is in error.
On datasheet page 4 under "Charge termination" it has example
termination %ages of ~ 5%, 7.5%, 10%, 20%.
This is good. Choose 20% for long life.
BUT the prog resistor values are all shown as 2k to 10k.
Somebody meant to fix this but never did.
This is a 2008 datasheet.

Same problem with precondition rate at top of page 4

I found 2006, 2007, 2008 versions of the data sheet.
All have the same errors in the above tables.
Version on uChip site claims to be 2009.
Is actuallt 2008.
Is wrong.

BUT

You can probably change charge rate as desired by changing Rprog
during charging.
You can probably set end current% cutoff by altering RProg once in
current taper mode.





           Russell McMahon









>
> Still poking around for protection circuits, and steers to good
> manufacturers would be appreciated.
>
> Thanks!
>
> Josh
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