Operating device for dimmably operating lamps, in particular one or a plurality of LED(s), - which device has a clocked converter circuit which comprises an energy storage element, a control circuit and at least one switch which is clocked starting from the control circuit, - the control circuit being designed to selectively operate the converter circuit, by means of controlling the switch, at least in a critical mode or in a discontinuous mode, - the control circuit being designed to set, in discontinuous mode, a re-switch-on time of the switch in discrete increments in one of the time ranges following the first zero crossing, in which time ranges a current through the energy storage element makes a rising zero crossing, and to adjust a feedback variable which influences the lamp output, by directly or indirectly changing a switch-on period of the switch in the event of an incremental change in the re-switch-on time, and the control circuit being designed to only change, in discontinuous mode, the re-switch-on time to a new calculated re-switch-on time, which differs from a current re-switch-on time of the switch, if the new re-switch-on time of the switch deviates from the current re-switch-on time by a period of time greater than a predefined value, and characterized in that the predefined value is a time period longer than 55% and preferably a time period longer than 62.5% of the period of a resonance oscillation of the current through the energy storage element during idle time of the clocked converter circuit. - which device has a clocked converter circuit which comprises an energy storage element, a control circuit and at least one switch which is clocked starting from the control circuit, - the control circuit being designed to selectively operate the converter circuit, by means of controlling the switch, at least in a critical mode or in a discontinuous mode, - the control circuit being designed to set, in discontinuous mode, a re-switch-on time of the switch in discrete increments in one of the time ranges following the first zero crossing, in which time ranges a current through the energy storage element makes a rising zero crossing, and to adjust a feedback variable which influences the lamp output, by directly or indirectly changing a switch-on period of the switch in the event of an incremental change in the re-switch-on time, and the control circuit being designed to only change, in discontinuous mode, the re-switch-on time to a new calculated re-switch-on time, which differs from a current re-switch-on time of the switch, if the new re-switch-on time of the switch deviates from the current re-switch-on time by a period of time greater than a predefined value, and characterized in that the predefined value is a time period longer than 55% and preferably a time period longer than 62.5% of the period of a resonance oscillation of the current through the energy storage element during idle time of the clocked converter circuit. to adjust a feedback variable which influences the lamp output, by directly or indirectly changing a switch-on period of the switch in the event of an incremental change in the re-switch-on time, and the control circuit being designed to only change, in discontinuous mode, the re-switch-on time to a new calculated re-switch-on time, which differs from a current re-switch-on time of the switch, if the new re-switch-on time of the switch deviates from the current re-switch-on time by a period of time greater than a predefined value, and characterized in that the predefined value is a time period longer than 55% and preferably a time period longer than 62.5% of the period of a resonance oscillation of the current through the energy storage element during idle time of the clocked converter circuit.