Abstract: The present disclosure relates to a circuit and a method for carrying out an alternating heating and capacitive measuring mode by a common heating wire, including carrying out a heating mode, wherein, due to a switching by a control circuit, first switching elements and second switching elements are connected in series to the heating wire, and the heating wire is connected, to one of two heating potentials; triggering a switchover from the heating mode into a measuring mode by the control circuit; carrying out the measuring mode, in which the measuring capacitance of the heating wire relative to a reference potential is determined by a detecting circuit by applying to the heating wire an alternating voltage; carrying out a testing phase by a test circuit that is switched by the control circuit that a test impedance is connected to the measuring capacitance.

Abstract: The present disclosure relates to a circuit and a method for carrying out an alternating heating and capacitive measuring mode by a common heating wire, including carrying out a heating mode, wherein, due to a switching by a control circuit, first switching elements and second switching elements are connected in series to the heating wire, and the heating wire is connected, to one of two heating potentials; triggering a switchover from the heating mode into a measuring mode by the control circuit; carrying out the measuring mode, in which the measuring capacitance of the heating wire relative to a reference potential is determined by a detecting circuit by applying to the heating wire an alternating voltage; carrying out a testing phase by a test circuit that is switched by the control circuit that a test impedance is connected to the measuring capacitance.

Abstract: A circuit structure and a method for carrying out an alternating heating and capacitive measuring mode by a common heating wire is presented. The method includes carrying out a heating mode, during which from a switching by a control circuit switching elements are in a conducting state, the switching elements are connected in series, so that the heating wire is supplied with a heating current from two different heating potentials; triggering a change into a detecting mode by the control circuit, so that the switching elements switch from the heating mode into a measuring mode, during which the switching elements are in a blocking state, so that the two different heating potentials are each interrupted several times; carrying out the measuring mode, in which the capacitance of the heating wire relative to a reference potential is determined by a detecting circuit by applying to the heating wire an alternating voltage.