Thomson Licensing

Thomson Licensing S.a.

Deutsche Thomson-brandt Gmbh

Kögel, Reinhard

Willinger, Frank

Hell, Melina

Reinhard Kögel

Jean-Paul Louvel

Wolfgang Hermann

Daniel Lopez

Jean Paul Louvel

Peter Scharlach

Melina Hell

Frank Willinger

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.

Switched mode power supply with soft start operation

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.

Power supply unit

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.

Switching DC-DC converter with parallel switches

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.

Power supply having two switch-mode power supply units

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 (T), coupled to the current input () of which are output voltages (U&#x2013;U) which are present both in the normal mode and in the standby mode and coupled to the control input of which are output voltages (U&#x2013;U) 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 () of this switching stage (T). 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 (U&#x2013;U) which are coupled to the current input () are monitored.

Protection circuit for a power supply unit, and power supply unit with a respective protection circuit

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

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.

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Brigachtal, Germany

Reinhard Kögel