Operating circuit for supplying at least one LED section (D10) having at least one LED, wherein the operating circuit has a control unit (SE') and a converter, preferably a buck converter, - wherein an electrical supply can be fed to the operating circuit at least at one input-side connection, and the operating circuit has at least one first switch (S1) of the converter which is clocked by the control unit (SE') and from which the at least one LED section (D10) can be electrically supplied, - wherein the control unit (SE') is configured to determine a first electrical parameter representing the anode voltage (V Bus ') of the at least one LED section at a first voltage divider (R11, R12) of the operating circuit, - wherein the control unit (SE') is configured to determine a third electrical parameter representing the current through the switch (S1) directly or indirectly at a measuring resistor (Rshunt) of the operating circuit, to determine the LED current (I LED ') through the at least one LED section (D10) as an actual value using the third electrical parameter, to compare the actual value with a target value (Itarget) and, depending on the comparison, to change a high-frequency clocking of the switch (S1), for example via PWM modulation, characterized in that - the control unit (SE') is further configured to determine a second electrical parameter representing the cathode voltage (Vx) of the at least one LED section by means of a filter circuit (R22, C22) of the operating circuit, wherein the filter circuit is a preferably analog low-pass filter of second or higher order or a band-pass filter, - the control unit (SE') is further configured to determine the voltage at the at least one LED section (V LED ') from the first and the second electrical parameter, - the control unit (SE') is further configured to determine the LED current (I LED ') from the product of the first electrical parameter and the third electrical parameter, divided by the voltage (V LED ') at the at least one LED section. - wherein an electrical supply can be fed to the operating circuit at least at one input-side connection, and the operating circuit has at least one first switch (S1) of the converter which is clocked by the control unit (SE') and from which the at least one LED section (D10) can be electrically supplied, - wherein the control unit (SE') is configured to determine a first electrical parameter representing the anode voltage (V Bus ') of the at least one LED section at a first voltage divider (R11, R12) of the operating circuit, - wherein the control unit (SE') is configured to determine a third electrical parameter representing the current through the switch (S1) directly or indirectly at a measuring resistor (Rshunt) of the operating circuit, to determine the LED current (I LED ') through the at least one LED section (D10) as an actual value using the third electrical parameter, to compare the actual value with a target value (Itarget) and, depending on the comparison, to change a high-frequency clocking of the switch (S1), for example via PWM modulation, - the control unit (SE') is further configured to determine a second electrical parameter representing the cathode voltage (Vx) of the at least one LED section by means of a filter circuit (R22, C22) of the operating circuit, wherein the filter circuit is a preferably analog low-pass filter of second or higher order or a band-pass filter, - the control unit (SE') is further configured to determine the voltage at the at least one LED section (V LED ') from the first and the second electrical parameter, - the control unit (SE') is further configured to determine the LED current (I LED ') from the product of the first electrical parameter and the third electrical parameter, divided by the voltage (V LED ') at the at least one LED section. <EOS>