Abstract: A circuit assembly for connection to a current source, preferably a 4-20 mA current loop and/or a high-impedance voltage source, preferably a high-impedance voltage source comprising an internal resistance greater than or equal to 100 ohms, includes at least one boost converter with a coil, a diode, in particular a flyback diode, which is connected in series with the coil, an output-side storage capacitor for summing an output voltage, and a switching element for connecting the coil to ground; a circuit part for dynamically controlling the switching element of the boost converter, wherein the circuit part is at least designed to control the switching element of the boost converter in a start-up phase such that the current source directly charges the storage capacitor via the coil until a predefinable reference value is reached.

Abstract: A method of monitoring a state of charge of a battery of a field device wherein the field device includes the battery, a voltage converter and a battery-powered component connected to the voltage converter, is disclosed. The method includes enabling the voltage converter and subsequently operating the voltage converter in duty cycles based on a current flowing from the battery to the voltage converter by repeatedly: disabling the voltage converter when the current exceeds an upper limit and enabling the voltage converter again when the current drops below a lower limit; and at least once determining and providing a state of charge of the battery determined based on a duration of at least one first time interval during which the voltage converter was enabled during one of the duty cycles and a previously determined dependency of the durations on the state of charge of the battery.

Abstract: A method of monitoring a state of charge of a battery of a field device wherein the field device includes the battery, a voltage converter and a battery-powered component connected to the voltage converter, is disclosed. The method includes enabling the voltage converter and subsequently operating the voltage converter in duty cycles based on a current flowing from the battery to the voltage converter by repeatedly: disabling the voltage converter when the current exceeds an upper limit and enabling the voltage converter again when the current drops below a lower limit; and at least once determining and providing a state of charge of the battery determined based on a duration of at least one first time interval during which the voltage converter was enabled during one of the duty cycles and a previously determined dependency of the durations on the state of charge of the battery.