Abstract: The present invention refers to a circuit for current and voltage control in a switching power supply controlled on the primary side, comprising a transformer with a primary-sided and a secondary-sided main winding, wherein energy pulses are transmitted from the primary side to the secondary side. Furthermore, a primary-sided switch switches on an off a primary current through the primary-sided main winding. A primary current comparator determines a switch-off time of the switch depending on the primary current. In order to reduce the load dependency of the output voltage, the control variable is variably amplified by a feedback network and additionally the control variable is reduced depending on the output load through a correction network.

Abstract: This invention relates to a control circuit for the closed-loop control of an output voltage of a primary-controlled switched-mode power supply as well as an associated method. The switched-mode power supply comprises a primary-side switch and a transformer with at least one auxiliary winding in which an auxiliary voltage is induced after opening the primary-side switch. The voltage induced in the at least one auxiliary winding provides the basis for the measurement voltage passed to the control circuit and for the supply voltage of the control circuit. The invention also refers to an associated switched-mode power supply.

Abstract: The present invention relates to a battery charger for charging a battery. The present invention especially relates to a battery charger comprising a switching power supply controlled on the primary side and a charge monitoring circuit for monitoring the charge state of the battery. For providing an improved battery charger which allows a secure and reliable charging of batteries with a reduction of the circuit complexity, the costs for appliances and the construction size, the charge monitoring circuit is—according to the invention—disposed in the switching circuit on the primary side of the battery charger.

Abstract: The present invention relates to a method for controlling the output voltage of a primary-controlled switched-mode power supply unit having a primary-side switch and a transformer with an auxiliary winding in which an auxiliary voltage which images the output voltage is induced after the primary-side switch is opened. The voltage induced in the auxiliary winding is fed to a control circuit as the control variable. The present invention also relates to a control circuit for performing such a control method and to an associated switched-mode power supply unit. To adjust the output voltage and the output current in the simplest and most economical way while minimizing the cost of the components needed, the switching frequency of the primary-side switch is so adjusted in dependence on the auxiliary voltage in the present invention that the output voltage and the output current of the switched-mode power supply unit adopt values in accordance with a predetermined output characteristic.

Abstract: The present invention relates to a control circuit for controlling the output power of a primary-controlled switched mode power supply unit, which comprises a primary switch and a transformer with an auxiliary winding. Within the auxiliary winding, voltage pulses are induced by primary-sided switching operations, which can be taken into account when controlling the output power. In order to provide an improved control and an enhanced flexibility with respect to the operational parameters, the sampling instance is determined based on the duration of the voltage pulse at the auxiliary winding during a previous switching cycle. In order to detect a defective contact between the auxiliary winding and the control circuit in a particularly simple and secure manner, the negative voltage pulse at the auxiliary winding occurring when the switch is closed may be used for confirming a proper connection.

Abstract: The present invention relates to a control circuit for controlling the output voltage of a switched mode power supply which comprises a primary-side switch and a transformer with a primary winding and a secondary winding. The output voltage of the switched mode power supply is adapted to be tapped at a capacitor which is connected in parallel to said secondary winding. The control circuit is adapted to be connected to a connection of the capacitor and a connection of the secondary winding, said control circuit being a controllable synchronous rectifier. Making use of this control circuit, an improved control accuracy can be achieved and an existing residual ripple of the output voltage can be compensated.