Direct AC driving circuit and luminaire
AssigneesTridonic GmbH & Co KG, Tridonic Jennersdorf GmbH
InventorsQuentin Lin, Istvan Bakk
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Abstract
The invention relates to a direct AC driving circuit and a luminaire for driving at least one LED, the driving circuit comprises a LED string (2) that comprises a series connection of at least two LEDs, wherein the LED string (2) is directly powered from a rectified AC mains voltage and a LED string switching unit (1) that is configured to control at least one LED shortening unit (1′) that is arranged in parallel to at least one LED of the LED string (2′). According to the invention, the driving circuit comprises means configured to provide a low supply voltage (VLow) which is also derived from the rectified AC mains voltage (4), wherein the low supply voltage (VLow) is generated from unutilized voltage of the LED-string (2′).
Claims17
A direct AC driving circuit for driving at least one LED, the driving circuit comprises:
- an LED-string that comprises a series connection of at least two LEDs, wherein the LED-string is directly powered from a rectified AC mains voltage;
- and
- an LED-string switching unit that is configured to control at least one LED-shorting unit that is arranged in parallel to at least one LED of the LED-string;
- and
- a low voltage power supply for providing a low supply voltage which is derived from the rectified AC mains voltage and is generated from unutilized voltage of the LED-string;
- wherein the low power supply includes a capacitor that is charged from unutilized voltage exceeding the sum of forward voltages of activated LEDS in the LED-string, and wherein the low supply voltage is derived from a further regulation means that is connected in series to the LED-string and that is independent of the LED-string switching unit.
A direct AC driving circuit for driving at least one LED, the driving circuit comprises:
- an LED-string that comprises a series connection of at least two LEDs, wherein the LED-string is directly powered from a rectified AC mains voltage;
- and
- an LED-string switching unit that is configured to control at least one LED-shorting unit that is arranged in parallel to at least one LED of the LED-string;
- and
- a low voltage power supply for providing a low supply voltage which is derived from the rectified AC mains voltage and is generated from unutilized voltage of the LED-string;
- wherein the low power supply includes a capacitor that is charged from unutilized voltage exceeding the sum of forward voltages of activated LEDS in the LED-string, and wherein the low supply voltage (VLow) is derived from a current control unit that is used to adjust the current flow through the LED-string.
Dependencies are inferred from the claim text.