公开(公告)号：WO2018206430A1

公开(公告)日：2018-11-15

申请号：PCT/EP2018/061515

申请日：2018-05-04

Applicant: PHILIPS LIGHTING HOLDING B.V.

Inventor： SAUERLAENDER, Georg ,  LIN, Zhuang ,  HATTRUP, Christian ,  LIU, Yuanqiang ,  DE BONDT, Guy, Louis, Paul ,  GUO, Zhaobin

IPC: H05B33/08

CPC classification number: H05B33/0812 ,  H05B33/083

Abstract: An LED driver is based on a linear driver for driving a controlled current from the mains input voltage whose rated value is fixed. The current flows in a time period during which the amplitude of the mains input voltage exceeds a forward voltage of the LED arrangement, and this time period has a low frequency variable duration, due to a variation of the input mains voltage at the low frequency, or due to a variation of the forward voltage of the LEDs. In one aspect the control circuit further controls the number of series LEDs driven by said drive circuit arrangement in dependence on the RMS value of the input mains voltage which varies at said low frequency, to provide a better efficiency, and the control circuit also adjusts the current in dependence on the variable duration and the LED forward voltage such that the average energy flow is controlled.