7:30
How exactly are you going to calibrate Rds(on) out in software, when it is highly variable?
The Vgs depends entirely on output voltage setpoint and the resistance is also going to vary with temperature.
Temp is the main thing but that's not a huge deal except for precision work. And it's reasonably linear so can be mapped in software reasonably well.
In this case with say a 10mohm Rds it's going to be an order of magnitude lower than the sense resistor, and then temp coeff is like a few percent of that over say a 50C range.
I deliberately didn't want to go into a tangent at that point.