Hello all, I'm part of the design team for a high-volume consumer=20
product that needs to run for several months on a single li-ion battery.=20
  As such, identifying quiescent current 'leaks' and checking that the=20
battery supplier is delivering batteries that meet specs is important.

Here's what I'd like to do, and prefer to buy vs. build, if the price is=20
sane ($hundreds fine, $thousands not).

I'd like to measure current into and out of the battery, the range is up=20
to 400mA going in when charging, and out of will be brief pulses of=20
150mA when doing RF transmit and down to 50uA when in a sleep state.

I'd also like to measure battery voltage to check the charge/discharge=20
curves under different operational scenarios.

So off the cuff, I'd say a 10 ohm sense resistor, ideally high-side but=20
low-side is ok, with differential connection to an amplifier that feeds=20
the A/D.  For the battery voltage, a 0-5V single-ended input is fine.

at 50uA a 10-ohm resistor gives 500uV, so some significant gain is=20
needed to get within typical A/D input ranges.

Overall accuracy isn't important; a few percent is fine.

Software-wise, something to save data points (several a second would be=20
nice, 100 a second would be great), draw graphs, and do basic math=20
(total power consumed) would be nice.

All this sounds like pretty typical data acq stuff, I've just not needed=20
to look at it until now.

I can build a differential amp to feed data acq with +-1V inputs if need=20
be, but I'd rather buy that.

USB connected, of course.  No need to do standalone logging or anything=20
fancy.

Anyone have suggestions?

Thanks all...!
J
--=20
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