I did some testing with the Particle Electrons’ PMIC and got some results that differ from what I would expect from the PMIC datasheet. According to the datasheet of the BQ24195 it states the following efficiency chart (see attachement). It’s clearly visible that at a current draw from approx >1A , 5V input voltage is ± 5% more efficient compared to powering at 12V. Now I ran a power consumption test (see chart second attachment) and checked it both with a multimeter and power supply power draw. It seems that powering at 12V is almost 80% less efficient compared to 5V at low load?
My question: what’s the reason for this? A possible explanation could be that the PMIC draws more current at 5V compared to 12V and the lower the current draw (sub 50mA) ,the more power inefficient the PMIC becomes(operating at the extreme left part of the graph “gray zone”). But i’m not really sure if that’s the real reason. The reason I’m asking is I have 12V available but I want to power the electron as efficient as possible (without bypassing the PMIC). If this requires adding an extra switching regulator to 5V, so be it.
Test setup: Particle Electron connected to the cloud, no battery (load) connected, empty loop code running