On Sat, Mar 08, 2008 at 08:11:12PM -0300, Werner Almesberger wrote: > In order to better understand what's happening with our power management, > I profiled USB and battery current during the boot process: > > http://people.openmoko.org/werner/usb-batt.html > > (USB on top, battery below.) > > This is GTA02v5 without SIM card running roughly the daily build from > about one week ago. At the end, I let the system sit still for a moment > so that it would begin to charge the battery, then I logged in with SSH > and suspended it. > > Negative battery current means that we're charging, positive that we're > discharging. The unloaded (simulated) battery voltage is 3.6V throughout > all this. (Inner resistance is ~600mOhm - about twice than a real > battery.) > > The x axis counts samples. Note that one of the two meters is a bit > slower than the other. The y axis shows amperes. Integration time is > 4ms, so we'll miss any really fast transients. > > What's interesting here is that we only draw a maximum of about 290mA > from USB, which is quite conservative (that is, if we're cleared to get > 500mA).
It doesn't depend only on usb power constraints, it has more to do with your pm chip. I had a device that could charge with up to 1A if connected to a dedicated charger, although we can charge with up to 2.5A in that situation. -- Best Regards, Felipe Balbi [EMAIL PROTECTED] http://blog.felipebalbi.com
