Battery life & case design

Joerg Reisenweber joerg at
Thu Jul 3 01:59:22 CEST 2008

Am Mi  2. Juli 2008 schrieb Francesco Cat:
> FR only accepts 100 or 500 mA current I think. 
Nope, FR sets MAXIMUM USB current to either 0.1, 0.5, or 1A depending on 
what's detected to be connected. This doesn't mean it won't work with 600mA. 
Either you set FR to 500mA and lose ~100mA of power source, or you figure out 
what's going to happen when we push the limit to 1A and power source goes 
down with voltage at ~600mA until FR doesn't pull any more than that, might 
work too.
At least see wallcharger that CAN deliver 2A, but happily feeds FR with just 

> So yes, it will be 
> "powered" by it in the sense that the FR battery will have a longer
> life; but it should not be enought i think because the FR seems to
> need more than 100 mA and I don't think it will accept something like
> 250mA. It's 500 or 100.

You can set arbitrary USB current limits by software, overriding the built-in 
detection. So a current limit of 250mA or 630mA is perfectly feasible I 
think. See spec of PCF50633 PMU.

> BTW: 6.58 Volts??? Strange... It should provide 5Volts to simulate a USB...
YEP! You'll need a LDO-regulator for 5V. 6.5V will burn the device and give 
you a very expensive yet exclusive doorstopper.

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