An integrated processing unit is supplied by a power supply voltage present at the terminals of a capacitor configured to supply a maximum permissible voltage drop. A periodic pulse signal is generated having a period that is less than or equal to a current period determined from the maximum permissible voltage drop and a current consumption of the processing unit. The power supply voltage is compared with a threshold voltage at the pulse rate of the periodic pulse signal. A control signal generated from that comparison is delivered to the processing unit and has a first value when the power supply voltage is greater than or equal to the threshold voltage and a second value when the power supply voltage is less than the threshold voltage.