A radar level gauge comprising transceiver circuitry, a propagation device and processing circuitry for determining a value of the process variable based on a relationship between a transmit signal and a return signal. The gauge has a DC/DC converter connected to a power supply interface, and configured to convert a first voltage to a second voltage, lower than the first voltage, and an energy storage. The gauge further has a switch, connected between the DC/DC converter and the energy storage, the switch having a non-conducting state for disconnecting the energy storage from the DC/DC converter when the transceiver circuitry is active, and a conducting state for connecting the energy storage to the DC/DC converter only when the transceiver circuitry is inactive.