Needed to create a current measurement bloc on a VBAT supply (from 2V5 to 5V) that can measure from 1uA to ~500mA. The idea is to have multiple shunt resistors with different very precise values to split the current range. At lowest current, the greater resistor (far right) is inserted in the path and amplified voltage drop can be measured by ADC (and be converted to current value then). When current rises, the resistor is automatically removed from path by back to back P channel MOSFET. And so for the second resistor (middle). Finally, the third (far left) is always present to measure greater current. At below, a 3-channels ADC can measure op-amps output and based on the 3 values, easily deduce the current going through the path.
