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I am trying to perform some energy measurements using smartphone. And to make sure that I am performing my calculations correctly, I been trying to find any examples of typical power circuit in today's smartphones (schematic, block diagrams....).

In particular what I am concerned about, is how to calculate energy consumption of smartphones when USB is connected to the device (thus it is charging). In this case, I am not just seeing current drawn from smartphone alone but also from USB... and probably the current that is drawn now from smartphone's battery is less than what it would be without USB connected to the device. Another problem is that battery and USB provides different voltage levels (~3.8-4.1V from battery and 5V from USB).

So, if I do have USB connected (in particular for ease of performing measurements)... How can I calculate or at least approximate true consumption of energy by smartphone (when battery is used alone)? Summing up currents drawn from battery and USB probably will not be correct. That's why I am trying to find some example of power circuits that maybe can lead me to the right direction.

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  • \$\begingroup\$ I think it's going to be very difficult to make this measurement from the USB, as the charge controller may be putting energy into the battery, doing nothing, or even (rumored in some designs) charging the battery for a while, running the device off the battery, then returning to charging. \$\endgroup\$ – Chris Stratton Sep 2 '13 at 16:08
  • \$\begingroup\$ I do have probes connected to both USB (power wire) and Battery terminals. I am getting current readings from both. \$\endgroup\$ – GrigoriP Sep 2 '13 at 16:15
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That's going to be a difficult thing to reverse engineer out. As a starting point, try to figure out the power management IC to dig up the datasheet. Once you have that, you have a starting point.

One thing to ponder is-what is the phone doing in terms of UI/display/data transmission. All of these things will have a substantial impact on the power consumption. For example streaming a youtube video will draw more power than just waiting for an incoming call.

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