a power management circuitry for a radar level gauge including a first voltage converter , having a low - voltage end for receiving a drive voltage from a power interface and a high - voltage end for supplying an intermediate voltage higher than the required operating voltage , a temporary energy store arranged to be charged by the intermediate voltage , a second voltage converter , having a high - voltage end for receiving an input voltage from the energy store , and a low - voltage end for providing the operating voltage lower than the input voltage . by storing energy at a higher voltage , a different type of energy store may be used . as a consequence , the cost and start - up time of the energy store is significantly reduced .