A circuit arrangement is disclosed with a regulating circuit which is particularly used for regulating a resonant converter having a plurality of outputs. The arrangement includes a protective circuit that can be constructed with the least possible circuitry and cost. The regulating circuit is used for generating a pulse-width modulated regulation signal (20) in dependence on measuring signals (Va, Vb) present on inputs of the regulating circuit (20). The arrangement further includes a comparator circuit (212) for comparing the duty cycle (δ) of the regulation signal (20) with a predefinable maximum duty cycle value (δmax) and minimum duty cycle value (δmin), in which in case of a duty cycle (δ) situated outside the range between the maximum duty cycle value (δmax) and the minimum duty cycle value (δmin) the circuit arrangement delivers control information that corresponds to this exceeding of the range.