Hi Ignacio,
The impedance of the /FAULT pin can be calculated as Vol/Io. From the datasheet max Vol/Io = 0.4V/0.004mA = 100Ohms.
The impedance of the /FAULT pin can be calculated as Vol/Io. From the datasheet max Vol/Io = 0.4V/0.004mA = 100Ohms.