The invention under consideration refers to a circuit arrangement for a switch-mode power supply, wherein the switch-mode power supply has a primary side, which can be connected to a supply voltage, and a secondary side, which can be connected to a consumer, and wherein the circuit arrangement comprises a primary-sided switch, a control circuit for controlling the primary-sided switch and additional active primary-sided components. Furthermore, the invention under consideration also refers to a switch-mode power supply with an active primary-sided circuit arrangement of that type. In order to specify an improved circuit arrangement that overcomes the disadvantages of the known solutions and that makes it possible to assemble a switch-mode power supply in miniaturised form in a manner that is particularly simple and economical while still complying with applicable safety standards, the control circuit is formed by a first integrated semiconductor chip and the primary-sided switch and the additional components are integrated in at least one additional semiconductor chip, said semiconductor chip being separate from the control circuit and being arranged on a single circuit carrier shared with the control circuit.