An embodiment device comprises a processing circuit and IP circuitry coupled to a power supply line, wherein the IP circuitry has an IP circuitry supply threshold for IP circuitry operation. A supply monitor circuit is coupled to the power supply line to sense the voltage on the power supply line and to switch the processing circuit to a low-power mode as a result of a drop in the voltage on the power supply line. The supply monitor circuit comprises a threshold setting node and is configured to be deactivated as a result of the voltage on the power supply line dropping below a deactivation threshold level set at the threshold setting node. A threshold setting circuit is configured to apply to the threshold setting node of the supply monitor circuit the IP circuitry supply threshold as a result of the processing circuit being in the low-power mode.