A power supply system includes a power supply circuit, a sensor of the current flowing through a terminal of the power supply circuit and a protection circuit. The protection circuit includes a differentiator adapted to measure a slope of a current measurement signal and comprises a driving stage. The power supply circuit is configured to receive a disconnection signal and, alternatively, to electrically connect the internal components thereof to its terminal or electrically disconnect the internal components thereof from its terminal, as a function of the value of the disconnection signal.