Measuring current in a design used to be a bit tricky. But with modern semiconductors this is no more effort than a tiny module with an I2C bus. It only
needs three resistors and two capacitors. I used this IC in the USB Power Monitor. (Scroll down for Cal register calculator.)
The trick is done with the INA226 by Texas instruments. The chip can be obtained as free sample.
Two tiny PCBs.
The only challenging part is the very small IC package. Here a microscope pic of the PCB. This is without tining.
It is possible to use different shut resistors depending on the current resolution one needs. The cal register of the INA226 needs to be calculated
accordingly. Values from 5mOhm to 50mOhm should be fine. The formula can be obtained in the datasheet.
Here is a little INA226 calculator:
Here is a little INA226 calculator:
| Resolution: | mA | |
| Rshunt: | mOhm | |
| Cal value: |
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