Thomson Licensing

Thomson Licensing S.a.

Deutsche Thomson-brandt Gmbh

Wolfgang Hermann

Jean-Paul Louvel

Michael Meitzner

Reinhard Kögel

John Stolte

Michel Thibault

Jean Paul Louvel

Peter Scharlach

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.

Circuit arrangement having a power supply unit

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.

Switched-mode power supply comprising an adjustable oscillator

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. Since the output voltages of the switched-mode power supply are each buffered by a capacitor, the relay is thus still open for a certain time after the arrangement has been switched off. The energy which is stored in the power factor coil is thus dissipated by the relay, by the coil drawing the current which is required to dissipate the energy from the mains via the relay.

Circuit arrangement with power factor correction as well as a corresponding appliance

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.

Switching DC-DC converter with improved stabilization

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.

Circuit arrangement with power factor correction, as well as a corresponding appliance

The power supply according to the invention has a first switched-mode power supply and a second switched-mode power supply, which is connected in parallel with the first, and with both switched-mode power supplies having power factor correction. In this case, the first switched-mode power supply has an active power factor correction circuit, for example with a current pump which contains a coil which is coupled to a primary winding of a transformer, and the second switched-mode power supply has a power factor coil (NS) in its power supply for power factor correction. Both switched-mode power supplies are in this case arranged in one appliance, in particular in parallel and downstream from a common mains switch. The active power factor correction in this case flattens the pulsed current flow, and the power factor coil shifts the phase of the pulsed current flow. Since the current flows in the switched-mode power supplies, which are connected in parallel, are added to one another, this addition results in additional broadening of the pulsed current flow, which leads to a further improvement in the power factor for the power supply, and/or the inductance of the power factor coil can in consequence be chosen to be correspondingly lower.

Power supply with a reduced harmonic load on the mains system, and a corresponding appliance

Switched-mode power supplies having a switching transistor and a transformer, with whose primary winding the switching transistor is connected in series, usually require a starting circuit, which is connected to an input voltage. Since a current continually flows through the starting circuit even during normal operation, it is endeavoured to keep the said current as small as possible. The switched-mode power supply comprises a threshold value circuit, for example a Zener diode connected in series with a resistor, which keeps the driver circuit turned off after the switching-on of the switched-mode power supply, until the operating voltage for the driver circuit has exceeded a specific threshold value which is referred to one end of a winding on the primary side. As a result of this, it is possible to charge a charging capacitor via the starting circuit with a low current, without currents flowing away. The threshold value circuit is advantageously connected by one end to that end of a secondary winding which, by means of positive feedback, assists the activation of the driver stage.

Switched-mode power supply with threshold value circuit

An integrated circuit achieves a burst mode standby operation for a switched-mode power supply by driving a switching transistor. One winding of a transformer is connected to inputs of two differently biased rectifier circuits and the sum of the output voltages of these circuits is applied to a control terminal of the integrated circuit.

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Tennenbronn, Germany

Wolfgang Hermann