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′).