The invention relates to a clocked flyback converter circuit for directly operating lighting means comprising: a transformer (5), which has a primary winding (4), which is coupled to a controllable switch (7), and a secondary winding (6), to which the lighting means (11) can be coupled; a control unit (14) for controlling the switch (7); and means (8) for directly or indirectly sensing the current through the switch (7) in the switched-on state and for feeding a signal and reflecting said current to the control unit (14). The control unit (14) is designed to switch off the switch (7) if the signal reflecting the current has reached a variable switch-off threshold (Is), to change the switch-off threshold (Is) in order to change the power transmitted by the flyback converter circuit (3), and to reduce the switch-off threshold (Is) for the current signal only down to a minimum value and to switch from operation in the limit mode to discontinuous operation in order to achieve a further reduction in the power transmitted by the flyback converter circuit (3) while the switch-off threshold (Is) is fixed.