Infineon Technologies Austria Ag

Tridonicatco Gmbh & Co Kg

Tridonic Gmbh Co. Kg

Werner Ludorf

Stefan Zudrell-Koch

Alexander Barth

Günter Marent

Peter Hein

Marco Seibt

A dimmable LED power supply circuit arrangement is disclosed. The circuit arrangement includes a flyback converter coupled between an input for receiving a rectified alternating line voltage and an output providing power for at least one LED device. The flyback converter includes a transformer and a semiconductor switch for switching a primary current of the transformer. A current sensing unit provides a current sense signal dependent on the primary current. A control unit controls the switching operation of the semiconductor switch dependent on the rectified alternating line voltage and the current sense signal such that the flyback converter operates in a quasi-resonant mode of operation, whereby the current sense signal is compared with a time-varying reference signal representing the rectified alternating line voltage and whereby a switch-off time of the semiconductor switch is determined dependent on the comparison.

Dimmable LED power supply with power factor control

Embodiments of the present invention relate to methods and circuits for brightness regulation for at least one light-emitting diode in the field of general lighting, more particularly, for incandescent lamp replacement by means of a supply voltage comprising a brightness level signal, wherein the brightness level signal contained in the supply voltage is decoded and converted into a modulation signal with a duty cycle corresponding to the brightness level signal for the purpose of driving a driver circuit for the at least one light-emitting diode.

Method and apparatus for regulating the brightness of light-emitting diodes

In an electronic ballast the output d.c. voltage (U) of a PFC intermediate circuit () is to be regulated. The intermediate circuit () has a clocked switch (S) which is controlled by a regulation circuit (). The regulation circuit () includes two counters (Z, Z). The counter (Z) has a greater number of count stages than the counter (Z). The counter (Z) is counted upwards or downwards in dependence upon the regulation difference. The counter (Z) is repeatedly counted only in one direction and for example reset by a reset signal. By comparing the counts of corresponding count stages of the two counters (Z) and (Z) in a comparator, the switch on time (t) for the clock switch (S) is determined.

Electronic ballast and operating method for a gas discharge lamp

In a circuit configuration to operate a gas discharge lamp (LA) the lamp (LA) is arranged in a full bridge circuit. A control circuit in normal operation actuates the four switches (S -S ) in such a way that it changes over with a first frequency (f ) alternately between a first and a second state (T , T ), whereby in the first state (T ) the two switches (S , S ) of a first bridge diagonal are opened, one switch (S ) of the second bridge diagonal is closed and the other switch (S ) with a second frequency (f ), which is higher than the first frequency (f ), is alternately opened and closed. In the second state (T ) the four switches (S -S ) are actuated in such a way that the lamp (LA) is pole reversed. In a start phase (T ) on the contrary the switch connected to the DC voltage source (S ) of a half-bridge is opened, the second switch (S ) of this half-bridge is closed, and the two switches (S , S ) of the other half-bridge are with a third frequency (f ) alternately opened and closed. As a result reliable lamp starting is rendered possible and at the same time the generation of high-frequent alternating fields in normal operation is reduced.

Circuit configuration to operate a gas discharge lamp

The invention relates to a control circuit for at least one light-emitting diode ( ) for adjusting the current and/or the voltage of the light-emitting diode ( ) to a desired value adjusted by means of a controller ( ), the current, the voltage and/or the luminescence of the light-emitting diode ( ) being detectable and comparable with the desired value.

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Ruhpolding, Germany

Werner Ludorf