recently I have found an interesting MPPT Lipo charging IC with an integrated 3.3V LDO
So I have bought the Buck-Boost eval. Board(Datasheet) for few tests.
For my tests I used a 6.2V power supply, deactivated the LDO and connected a 3.7V Lipo to see how high the charging current is. With my Ampere meter I measured 30mA battery charging current which seems to be a little bit to low. So i put a 2.2Ohms resistor in series to the DC/DC inductor to measure the current of the inductor(schematic page 4 and 5). The pic below shows the voltage across the resistor. My calculations for the inductor current are
Now as you can see, my battery is charged with 30mA but my DCDC converter provides about 85mA. So how comes the difference and what happens with the remaining 50mA?