Abstract: A switched-mode power supply with a burst mode comprises an integrated circuit (Ic) with a minimal number of terminals. The integrated circuit (Ic) comprises a switching element (S) for periodically switching on and off the current (Id) in a primary winding (Lp) of a transformer (T), and a control circuit (Cc) for controlling the on and off-switching of the switching element (S). The integrated circuit (Ic) has three terminals (T1, T2, T3). A main current path of the switching element (S) is arranged between two of the terminals (T1, T2). A capacitor (C1) is connected to the third terminal (T3). A capacitor voltage (Vc) across the capacitor (C1) is used as power supply voltage for the control circuit (Cc). A feedback circuit (Fb) has an input connected to a DC output voltage (Vout) supplied by a secondary winding (Ls) of the transformer (T), and an output connected to the third terminal (T3).

Abstract: A switched-mode power supply specially suitable for supplying a low output power. The switched-mode power supply periodically first charges a capacitor (C) from an input voltage (Vin) during a first period of time (T1), and then forms a resonant circuit, including the capacitor (C) and an inductor (L), to transfer the charge in the capacitor (C) to a load (Z) via a rectifier during a second period of time (T2).

Abstract: A switched-mode power supply circuit having a transformer and a first controllable switch on the primary side of the transformer. A first section is in the form of a flyback d.c. converter including a first secondary winding of the transformer for generating a first d.c. output voltage which is stabilized, by a control, against d.c. input voltage variations of the circuit and of a first load. A second section including a second secondary winding of the transformer constitutes a forward d.c. converter having a second controllable switch for generating a second d.c. output voltage. The ratio between the period of conductance of the second switch and the period of the control signal of the first switch is independent of the frequency of this signal.