Circuitry for detecting faults in a system for supplying power from an input node to an output node and having at least one switch coupled between the input node and the output node. The fault detecting circuitry is configured for indicating a fault condition of the switch when the switch is commanded to turn on and at least one of the following conditions is detected: a voltage across the switch exceeds a predetermined value or a value of the switch control signal is insufficient to turn the switch on. The fault condition is indicated only if the detected condition is present for a predetermined period of time.