OPERATING CIRCUIT WITH CLOCKED CONVERTER FOR ACTUATING AN LED SECTION

The invention relates to an operating circuit for an LED section having at least one LED, wherein - a supply voltage (Vbus) can be fed to the operating circuit at at least one input side connection, and the operating circuit has a coil (LBuck) and a first switch (LS) clocked by a first control unit (SE), wherein - energy is buffered at the conductively connected first switch (LS) in the coil (LBuck), said energy discharging at the non-conductively connected first switch (LS) via a diode (D1) and via the LED section, wherein - the control unit (SE) is configured to determine the switch current (ILS) through the first switch (LS) at a first measuring resistance (Rshunt), preferably the supply voltage (Vbus) at a second measuring resistance (R VbusShunt) and preferably a measuring voltage (Vled) at the LED section at a third measuring resistance (RvledShunt), and to calculate therefrom the LED current (ILED) through the LED section, wherein the switch current (ILS) is combined with a PWM signal, wherein the PWM signal is low-frequency relative to the frequency of the switch current (ILS), where a second switch (FS) is provided which is configured to enable a current path between the first measuring resistance (Rshunt) and a low-pass filter (TPF) only during a switch-on period of the PWM signal, and to interrupt the signal path during a switch-off period of the PWM signal.