Abstract: A flyback converter including a transformer (T.sub.r), having a primary winding (W.sub.P) and having a secondary winding (W.sub.S), wherein the primary winding is connected in series with a controlled switch (T) and an actuation circuit (A) to an input direct voltage (U.sub.P), and the secondary winding is connected in series with a rectifier (D.sub.S) and, downstream of the secondary winding, a charging capacitor (C.sub.S); the actuation circuit (A) supplies start pulses of a fixed frequency for the switch, has a current sensor (R.sub.P) for the current through the primary winding. Coupled with the secondary winding is a first rectifying amplifier (K.sub.U) for comparing the output voltage (U.sub.S) with an adjustable voltage reference value (U.sub.RefU) and a second rectifying amplifier (K.sub.I) for comparing the output current (I.sub.S) with a adjustable current reference value (U.sub.