Circuit arrangement having a voltage converter having an input path which is suitable for providing an input voltage (U IN) to the voltage converter, an output path which is suitable for tapping off an output voltage (U OUT) from the voltage converter, wherein the voltage converter at least three phases connected in parallel and each having at least one half-bridge in connection with a coil and a capacitor, or having at least two phases connected in parallel and each having at least two half-bridges in connection with a coil and a capacitor, wherein a fuse and a MOSFET are arranged in each branch of the half-bridges, a. characterized b. in that the circuit arrangement has a first switch arranged in series in the input path of the voltage converter and/or a second switch arranged in series in the output path of the voltage converter, and wherein the circuit arrangement is configured c. to identify a defect of a low-side MOSFET or a defect of a high-side MOSFET in a branch of a half-bridge of a phase, and d. to stop the actuation of all MOSFETs, and e. to open the second switch in the case of a defect of one of the low-side MOSFETs, or to open the first switch in the case of a defect of one of the high-side MOSFETs, and f. to actuate the MOSFETs of the phases in which all MOSFETs are intact in such a way that a sufficiently large current flows into the phase with the defect in order to trip the fuse. at least three phases connected in parallel and each having at least one half-bridge in connection with a coil and a capacitor, or having at least two phases connected in parallel and each having at least two half-bridges in connection with a coil and a capacitor, wherein a fuse and a MOSFET are arranged in each branch of the half-bridges, a. characterized b. in that the circuit arrangement has a first switch arranged in series in the input path of the voltage converter and/or a second switch arranged in series in the output path of the voltage converter, and wherein the circuit arrangement is configured c. to identify a defect of a low-side MOSFET or a defect of a high-side MOSFET in a branch of a half-bridge of a phase, and d. to stop the actuation of all MOSFETs, and e. to open the second switch in the case of a defect of one of the low-side MOSFETs, or to open the first switch in the case of a defect of one of the high-side MOSFETs, and f. to actuate the MOSFETs of the phases in which all MOSFETs are intact in such a way that a sufficiently large current flows into the phase with the defect in order to trip the fuse. a. characterized b. in that the circuit arrangement has a first switch arranged in series in the input path of the voltage converter and/or a second switch arranged in series in the output path of the voltage converter, and wherein the circuit arrangement is configured c. to identify a defect of a low-side MOSFET or a defect of a high-side MOSFET in a branch of a half-bridge of a phase, and d. to stop the actuation of all MOSFETs, and e. to open the second switch in the case of a defect of one of the low-side MOSFETs, or to open the first switch in the case of a defect of one of the high-side MOSFETs, and f. to actuate the MOSFETs of the phases in which all MOSFETs are intact in such a way that a sufficiently large current flows into the phase with the defect in order to trip the fuse.