Abstract: The circuit arrangement has a power supply unit, a mains switch and a switching element, for example a relay, that bridges a first switching contact of the mains switch. A load is coupled to a control terminal of the switching element, so that when the control voltage is turned off for the purpose of opening the switching element, the load is simultaneously turned off. The circuit arrangement contains a microprocessor, in particular, which is supplied with an operating voltage by the power supply unit, and which is coupled to the control terminal of the switching element for control of the switching element. The load is a fan, for example, which is switched off in a delayed manner when the circuit arrangement is switched off by means of the mains switch.

Abstract: The circuit arrangement has a power supply unit, a mains switch and a switching element, for example a relay, that bridges a first switching contact of the mains switch. A load is coupled to a control terminal of the switching element, so that when the control voltage is turned off for the purpose of opening the switching element, the load is simultaneously turned off. The circuit arrangement contains a microprocessor, in particular, which is supplied with an operating voltage by the power supply unit, and which is coupled to the control terminal of the switching element for control of the switching element. The load is a fan, for example, which is switched off in a delayed manner when the circuit arrangement is switched off by means of the mains switch.

Abstract: The switched-mode power supply has a transformer which contains a primary winding and at least one secondary winding, a switching transistor in series with the primary winding, a driver stage for controlling the switching transistor, and a control circuit for controlling an output voltage. The control circuit in this case contains an oscillator which can be adjusted via a connection and is coupled to a secondary winding in order to determine the time at which the switching transistor is switched on. A switching stage is, in particular, arranged between the connection and the secondary winding and passes on a supply voltage to the connection when a sudden voltage change occurs on the secondary winding at the time of an oscillation. In consequence, the switching transistor is switched on at a time at which the losses when switched on are low, thus considerably reducing the losses which occur in the switching transistor.

Abstract: A PFC circuit using a step down regulator includes an input port receiving input AC mains voltage, an output port providing an output DC mains voltage, a mains rectifier connected to the input port, a step down circuit connected to the mains rectifier for providing the output DC mains voltage to the output port, a switch connected to the step down circuit, a current source circuit generating a current signal corresponding to a level of the output DC mains voltage, a current sense resistor connected to the switch to provide a voltage signal corresponding to a level of a current flowing through the switch, and a PFC control unit receiving the current signal and the voltage signal and controlling the switch in accordance therewith to selectively enable and disable the step down circuit. The PFC circuit according to the present invention reduces the supply voltage of the SMPS and thus reduces the size of the SMT device and the cost for making such SMT device.

Abstract: The circuit arrangement has a mains connection, a mains switch and a switched-mode power supply which contains a power factor coil for power factor correction. In this case, the mains switch has two switching contacts, one of which is arranged in a supply line between the mains connection and the switched-mode power supply, and in this way switches the phase or neutral conductor of the 50 Hz line network off and on. The connections of the second switching contact are located in a voltage supply for the driver circuit of the switched-mode power supply, and the second switching contact switches the switching transistor in the switched-mode power supply off when the circuit arrangement is switched off, by its control voltage being switched off directly or indirectly. The switching contact of a relay is arranged in parallel with the first switching contact of the mains switch, and the control coil of this relay is connected to an output voltage of the switched-mode power supply.

Abstract: The switched-mode power supply has a transformer which contains a primary winding and at least one secondary winding, a switching transistor in series with the primary winding, a driver stage for controlling the switching transistor, and a control circuit for controlling an output voltage. The control circuit in this case contains an oscillator which can be adjusted via a connection and is coupled to a secondary winding in order to determine the time at which the switching transistor is switched on. A switching stage is, in particular, arranged between the connection and the secondary winding and passes on a supply voltage to the connection when a sudden voltage change occurs on the secondary winding at the time of an oscillation. In consequence, the switching transistor is switched on at a time at which the losses when switched on are low, thus considerably reducing the losses which occur in the switching transistor.

Abstract: The circuit arrangement has a mains connection, a mains switch and a switched-mode power supply which contains a power factor coil for power factor correction. In this case, the mains switch has two switching contacts, one of which is arranged in a supply line between the mains connection and the switched-mode power supply, and in this way switches the phase or neutral conductor of the 50 Hz line network off and on. The connections of the second switching contact are located in a voltage supply for the driver circuit of the switched-mode power supply, and the second switching contact switches the switching transistor in the switched-mode power supply off when the circuit arrangement is switched off, by its control voltage being switched off directly or indirectly. The switching contact of a relay is arranged in parallel with the first switching contact of the mains switch, and the control coil of this relay is connected to an output voltage of the switched-mode power supply.

Abstract: Switched-mode power supplies require a power factor correction circuit in order to comply with anticipated regulations for the harmonic load on the line network. In its second current path, which produces a connection between a rectifier element and a tap on the primary winding of a transformer, the switched-mode power supply contains a capacitor which produces current limiting for an inductance in this current path. When the switching transistor is in the switching mode the inductance is charged, when the switching transistor is switched on, in the sense of an energy store until the capacitor is charged. When the switching transistor is switched off, the inductance and the capacitor are discharged via a diode in the direction of an energy-storage capacitor.