Tdk-lambda Americas Inc.

Ciro Lee Sirio

Eleftherios Doudousakis

A drive circuit includes a DC/DC converter, an outer control loop providing an output voltage representing a comparison between a load current and a reference voltage, a multiplier multiplying the outer control loop output voltage with a sample of the rectified output and provide an output current, a current amplifier comparing an input line current sample and the multiplier output current, a comparator driving the switch with a modulated output based on the current amplifier output and a sawtooth reference, and an upper voltage limit loop having an output in electrical communication with the outer control loop output, wherein the outer control loop output voltage is impacted by the upper voltage limit loop output during a zero load scenario. The drive circuit also includes a line voltage transformer and a lightning suppression circuit coupled to the voltage rectifier output.

Drive circuit for high-brightness light emitting diodes

A zero voltage switch half bridge converter comprises a first and second diode series diodes, parallel with a voltage source. A first terminal of an inductor is joined to the diode junction. A first semiconductor auxiliary switch connected in series between the voltage source and a third diode, which is in series with a fourth diode connected to a second semiconductor auxiliary switch. First and second semiconductor main switches are connected in series and in parallel with the voltage supply. A capacitive voltage divider connected across the voltage source, wherein a second terminal of the inductor is connected to junction of the main switches and a midpoint of the capacitive voltage divider. A control circuit is configured to provide respective control signals to at least the first semiconductor auxiliary switch and the second semiconductor auxiliary switch.

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Huntington, NY, United States of America

Ciro Lee Sirio