Circuit, comprising: a DC-to-DC converter; and an input circuit, which is connected upstream of the DC-to-DC converter and has a first connection and a second connection for connection to a voltage supply, and a third connection and a fourth connection for connection to the DC-to-DC converter; wherein the input circuit has a semiconductor element between the first connection and the third connection, wherein a first component connection of the semiconductor element is connected at least via a first capacitor and a second capacitor to a second component connection of the semiconductor element, wherein the input circuit furthermore has: means for controlling an on-state resistance of the semiconductor element by means of a voltage between the first component connection and the second component connection; means for damping an oscillation produced in the input circuit by the application of a voltage, which oscillation arises during testing of the circuit for robustness against surge voltages in the input circuit and causes a voltage fluctuation, wherein the damping comprises an increase, controlled by the voltage fluctuation, in the on-state resistance of the semiconductor element; characterized in that the input circuit is designed to damp the voltage fluctuation by means of a temporary increase in the on-state resistance in a negative half-cycle of the oscillation. a DC-to-DC converter; and an input circuit, which is connected upstream of the DC-to-DC converter and has a first connection and a second connection for connection to a voltage supply, and a third connection and a fourth connection for connection to the DC-to-DC converter; wherein the input circuit has a semiconductor element between the first connection and the third connection, wherein a first component connection of the semiconductor element is connected at least via a first capacitor and a second capacitor to a second component connection of the semiconductor element, wherein the input circuit furthermore has: means for controlling an on-state resistance of the semiconductor element by means of a voltage between the first component connection and the second component connection; means for damping an oscillation produced in the input circuit by the application of a voltage, which oscillation arises during testing of the circuit for robustness against surge voltages in the input circuit and causes a voltage fluctuation, wherein the damping comprises an increase, controlled by the voltage fluctuation, in the on-state resistance of the semiconductor element; means for controlling an on-state resistance of the semiconductor element by means of a voltage between the first component connection and the second component connection; means for damping an oscillation produced in the input circuit by the application of a voltage, which oscillation arises during testing of the circuit for robustness against surge voltages in the input circuit and causes a voltage fluctuation, wherein the damping comprises an increase, controlled by the voltage fluctuation, in the on-state resistance of the semiconductor element; characterized in that the input circuit is designed to damp the voltage fluctuation by means of a temporary increase in the on-state resistance in a negative half-cycle of the oscillation.