A USB source device, supporting USB Power Delivery mode and coupled to a USB receiver device, includes a power converter delivering a supply voltage and a capacitive network coupled to the power converter. A method for managing the supply voltage on an output power supply pin of the USB source device includes discharging the capacitive network so as to reduce the supply voltage in response to a request to reduce the supply voltage by the USB receiver device to a target voltage. The method also includes delivering, to the power converter, a setpoint voltage for the supply voltage, a value of the setpoint voltage being reduced non-linearly so as to keep a temporal variation of the setpoint voltage lower than that of the supply voltage.