Abstract: The switching DC-DC converter comprises an inductor, a diode, a transistor and an integrated control circuit with an output switch, the output switch and the diode being coupled to the inductor for providing a DC output voltage. The transistor is coupled with a current input to an input voltage, with a control input to a current input of the output switch, and with a current output to a current output of the output 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 power supply has first and a second switch-mode power supply (SMPS) units, which both contain a transformer having a primary winding and at least one secondary winding, and a driver stage. The power supply furthermore has a normal operating mode, in which both SMPS units are in operation, and a standby operating mode, in which the first SMPS unit is switched off by a control voltage. In the standby mode, the control voltage is also used to reduce the switching frequency of the second SMPS unit, for example by means of a connection, which reduces the oscillation frequency of the oscillator of the second driver stage. In a preferred exemplary embodiment, the output of a first driver stage is furthermore connected via a series circuit to the oscillator input of a second driver stage, for synchronization purposes.

Abstract: The switched mode power supply comprises an inductor, a switching transistor, a controller circuit coupled to the switching transistor, a rectifying means and a feedback regulation loop for providing a stabilised output voltage. It comprises further a protection circuit coupled to an output or input of a comparator of the controller circuit for providing an overvoltage protection in case of a failure of the regulation loop. The protection circuit comprises in particular an integrating circuit and a comparating circuit. In a preferred embodiment, an output of the protection circuit is coupled to a sense input of the controller circuit, for switching off the controller circuit immediately in case of a failure. In another aspect of the invention, the protection circuit comprises further a second comparator coupled to the first comparating circuit for the surveillance of the input voltage of the switched mode power supply, and for the detection of a short circuit of the inductor or the rectifying means.

Abstract: The switching converter contains a switching transistor, a first inductance and a first diode, which are connected so as to form a step-down converter for the purpose of producing a first rectified output voltage from an input voltage. The switching transistor is connected on the input side to the input voltage via a second inductance, and a second diode is coupled to a tap being arranged between the second inductance and the switching transistor for the purpose of producing a second rectified output voltage. The second rectified output voltage is in this case unregulated, but can be used in particular as a supply voltage for a television tuner.

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 for degaussing a picture tube comprises a degaussing coil (ES), a single PTC element (T) and a switch (R), the degaussing coil (ES), the single PTC element (T) and the switch (R) being connected in series For a degaussing, the degaussing coil (ES) is activated by means of the switch (R) for a defined time interval such that the switch-off takes place at an ampere-turns product of greater than 5.

Abstract: The switched mode power supply contains a transformer, which has a primary winding and at least one secondary winding, a switching transistor in series with the primary winding and a control circuit for controlling an output voltage of the switched mode power supply. The control circuit contains an oscillator, whose oscillation frequency can be set via a terminal, and which is coupled to a secondary winding of the transformer. The wiring for the terminal is connected such that the switched mode power supply starts up at a relatively low oscillation frequency once it has been connected, and, during operation when an additional voltage is supplied to the input via the secondary winding, the oscillation frequency of the switched mode power supply is increased. The terminal is connected in particular via a bandpass filter to a voltage generated by the secondary winding.

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 protection circuit serves for the monitoring of output voltages of a power supply unit which has a normal mode and a standby mode. The protection circuit comprises a first switching stage (T1), coupled to the current input (1) of which are output voltages (U5–U8) which are present both in the normal mode and in the standby mode and coupled to the control input of which are output voltages (U1–U3) which are only present in the normal mode. A control signal (Us), by which the power supply unit is switched over between normal mode and standby mode, is coupled to the control input (2) of this switching stage (T1). As a result, by means of the control signal, the output voltages which are only present in the normal mode are blocked in the standby mode by the control signal, so that in the standby mode only the output voltages (U5–U8) which are coupled to the current input (1) are monitored.

Abstract: The switching DC-DC converter comprises an inductor, a control circuit with an oscillator and an output stage, the output stage being coupled to the inductor, a diode coupled to the inductor, and a feedback loop for generating a stabilized output voltage. An output voltage of the output stage is coupled with an oscillator input of the control circuit, for example via an impedance, for synchronizing an oscillation cycle of the oscillator with a current pulse of the output stage.

Abstract: The circuit arrangement comprises a driver stage and a control circuit coupled to the control input of a switching transistor. The driver stage provides a switching voltage for the operation of the switching transistor, and the control circuit provides a shaping of the switching voltage in the sense of delaying the switching through of the switching transistor. The control circuit comprises in particular a control transistor, which is coupled a control input via a high pass filter to the output of the driver stage and with an current input to the control input of the switching transistor. The switching transistor is for example a MOSFET being used for switching on and off a capacitive load.

Abstract: The power supply has a first and a second SMPS, which both contain a transformer having a primary winding and at least one secondary winding. The power supply furthermore has a normal operation, in which both SMPS units are in operation, and a standby operation, in which the first SMPS unit is switched off by a control voltage. In this case, the control voltage is simultaneously used to reduce the switching frequency of the second SMPS unit in standby operation, for example by means of a connection, which reduces the oscillation frequency of the oscillator of the second driver stage. In a preferred exemplary embodiment, the output of the first driver stage is furthermore connected via a series circuit to the oscillator input of the second driver stage, for synchronization purpose.

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: Embodiments of the invention provide a power supply unit that operates in a standby mode and in a normal mode. The power supply unit comprises a first power supply providing output voltages during the standby mode and a second power supply providing output voltages during the normal mode. A pre-converter provides a stabilized supply voltage for the first and second power supply. The pre-converter operates as an up-converter during the normal operation mode and is switched off during the standby mode together with the second power supply.

Abstract: The circuit arrangement comprises a power supply unit with a first power supply only for the analogue signal processing part and for the control part of a respective device. For the digital signal processing part, a second, separate switched mode power supply is provided, which is switched off, when only the analogue signal processing part is active, and which is in operation, when the digital signal processing part is on. For switching on and off of the second switched mode power supply, the power supply comprises a switching circuit (18), which is coupled in a special embodiment to a control loop (15) on the secondary side, for switching off the second power supply at the primary side via a galvanic isolating means (14). The switching circuit is provided with a supply voltage (12VS) from the first power supply and receives the on/off command from the control part, e. g. a microprocessor.

Abstract: The circuit arrangement has a mains connection, a mains switch with two switching contacts, a demagnetization coil and a switch-mode power supply, which contains a driver circuit for producing a control voltage for the switching transistor of the switch-mode power supply. A first switching contact of the mains switch is arranged between the mains connection and the demagnetization coil in order to switch the demagnetization coil on and off, and the second switching contact is connected to a supply or control voltage for the driver circuit, in order to switch off the switch-mode power supply. In consequence, a power factor coil can be used between the mains connection and the switch-mode power supply for power factor correction, without the mains switch being loaded by the inductance of the power factor coil.

Abstract: The protection circuit serves for the monitoring of output voltages of a power supply unit which has a normal mode and a standby mode. The protection circuit has here a first switching stage, coupled to the current input of which are output voltages which are present both in the normal mode and in the standby mode and coupled to the control input of which are output voltages which are only present in the normal mode. A control signal, by which for example the power supply unit is switched over between normal mode and standby mode, is coupled to the control input of this switching stage. As a result, by means of the control signal, the output voltages which are only present in the normal mode are blocked in the standby mode by the control signal, so that in the standby mode only the output voltages which are coupled to the current input are monitored.

Abstract: The switched-mode power supply contains a transformer, a switching transistor in series with the primary winding of the transformer, and a damping network on the secondary side, which has a connection for a further secondary winding via which energy is transferred from this damping network, by way of example, to a charge-storage capacitor which is coupled to this secondary winding. The connection is advantageously produced via a rectifying element, for example a diode, which is coupled after the rectifying diode (D5) for the second secondary winding. In a further exemplary embodiment, the diode in the series circuit, which is connected in parallel with the rectifier diode for the first secondary winding, is not coupled to the charge-storage capacitor for the first secondary winding, but is likewise coupled to the charge-storage capacitor for the second secondary winding.

Abstract: The switched-mode power supply according to the invention has a power factor correction circuit, which operates on the principle of a current pump and has a first coil for damping voltage spikes, as well as a second coil for power factor correction. The two inductances are in this case connected in series and are arranged on a coil former and on a common core. In one preferred exemplary embodiment, an E/E ferrite core is used as the core, and a coil former with chambers is used as the coil former, with the windings of the two inductances being arranged in different chambers. An empty chamber, which is located in the region of the air gap in the core, is advantageously arranged between the two inductances. This partially decouples the two inductances by means of the air gap, so that the damping response of the first inductance is better.