An operating circuit for at least one light-emitting diode (LED) incorporates a switched-mode regulator circuit to which a DC voltage is fed and which provides a supply voltage for the at least one light-emitting diode (LED) by means of a coil (L1) and a switch (S1) clocked by a control unit (SR). When the switch (S1) is on, energy is built up in the coil (L1), which is discharged through the at least one light-emitting diode (LED) when the switch (S1) is off. The control unit (SR) determines the time period between the switch (S1) switching off and subsequently switching on depending on the voltage across the at least one light-emitting diode (LED) and a temporally constant characteristic parameter of the coil (L1).