A circuit for operating at least one LED (“driver circuit”) includes input terminals to be connected to an input or operating voltage in the form of a direct current (DC) voltage or a rectified alternating current (AC) voltage, and output terminals to be connected to a load circuit containing the at least one LED. The circuit includes a clocked switch and an open-loop control circuit for clocking the switch. The open-loop control circuit is in the form of an integrated circuit (IC) and is provided with input and output pins. The open-loop control circuit generates a clock signal for the switch depending on at least two actual value signals, such that there is a control loop with the manipulated variable “clocking of the switch.”