A sensor circuit for a power FET monitors current flowing through the FET and includes a regulator circuit regulating a first current flowing through a sense resistance, so voltage drop at the sense resistance corresponds to voltage drop between terminals of the FET. A measurement circuit provides a second current corresponding (or being proportional) to the first current. A first switch selectively applies the second current to a resistor based on a first control signal, and a low pass filter generates a low-pass filtered signal by filtering voltage at the resistor. A voltage follower generates a replica of the low-pass filtered signal, and a second switch selectively applies the replica to the resistor. When the FET is closed, a control circuit closes the first switch and opens the second electronic switch. When the FET is opened, the control circuit opens the first electronic switch and closes the second electronic switch.