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USB charger - resistors
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Please be positive and constructive with your questions and comments.

USB charger - resistors

by imageer on Thu Sep 16, 2010 5:31 pm

Hi, I just got a couple of these boards, and before blowing something up, I wanted to confirm resisitors: if I wanted a 1000mA charge current, I'd use a 1k resistor, and 500mA would be 2k? :?
Thanks! :)

"The fast-charge current is 200mA by default, but is easily adjustable from 100mA up to 1000mA by soldering a through-hole resistor on-board."
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Re: USB charger - resistors

by adafruit on Thu Sep 16, 2010 7:51 pm

which charger are you using? the white one or the blue one?

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Re: USB charger - resistors

by imageer on Thu Sep 16, 2010 9:53 pm

This is the one I meant: USB LiIon/LiPoly charger - v1.1
http://www.adafruit.com/index.php?main_ ... cts_id=259

But now that I've seen the the other one:
USB/DC Lithium Polymer battery charger 5-12V - 3.7/4.2v cells
I'll get that as well, and so detailed info on charge current modification for both would be appreciated! Thanks! :)
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Re: USB charger - resistors

by adafruit on Thu Sep 16, 2010 10:10 pm

theres some info in the schematics... for the white one, 2Kohm -> 500mA 1K -> 1A
for the blue one, see this for a list
http://www.adafruit.com/datasheets/mcp73861.png

dont forget, this assumes you've removed the 10K onboard. if you're not going to do that, you need to calculate the two resistances in parallel to get the 'real' resistance

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Re: USB charger - resistors

by msaeed on Sun Sep 19, 2010 5:07 pm

I have having the same problem. so can we just make like alittle easier and remove the 10k and have only the 1K in place?
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Re: USB charger - resistors

by msaeed on Sun Sep 19, 2010 5:08 pm

oh wait thats what you just said... hah sorry
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Please be positive and constructive with your questions and comments.