Signify Holding B.v.

John Dai

Zhi Quan Chen

Liang Shi

Kelvin Wang

Shan Shan Wang

In order to reduce energy loss of a tapped linear driver, it is proposed an LED lighting circuit, comprising an input (Vbus, GND) adapted to receive an input voltage, a plurality of LED segments (LED, LED, LED, LED) connected in series and to the input, a buffer component (C) connected to an anode and a cathode of a series string of at least two of the plurality of LED segments with respective switches, a current source circuit (B) in series connection with a parallel connection of the buffer component (C) and the at least two LED segments, across the input; further comprising a further buffer component (C) across the current source circuit (B), wherein said buffer component (C) and the further buffer component (C) is in series connection.

LED lighting circuit and a lighting device comprising the same

A LED lighting circuit has a plurality of LED segments connected in series. A switching arrangement is used to selectively bypass at least one LED segment to implement a tapped linear driver approach. Degrading of a component in the LED lighting circuit is detected, so that a first TLD current modulation scheme is implemented when no such degrading is detected whereas a second current modulation scheme, different from the first current modulation scheme, is implemented to compensate for said degrading. Said degrading is leading to an increase in a turning on voltage of one LED segment, and compared to said first current modulation scheme, said second current modulation scheme has a higher voltage threshold at which said LED segment is switched. In this way, protection may be provided for circuit components and the light output may be maintained at the desired level in the event of component degrading, such as LED chip failure or contact resistance changes.

Growing community of inventors

Shanghai, China

John Dai