Lighting device with timing circuit synchronisation

Abstract

A timing circuit (), in particular a real time clock circuit, in a lighting device () that is periodically () powered from a main power supply () in accordance with a power supply cycle having a power-on time and a power-off time, is automatically synchronized in case the power condition of an auxiliary power supply () is insufficient to assume correct operation of the timing circuit (). At each power-on of the power supply cycle, a power condition of the auxiliary power supply () is monitored. If the determined power condition exceeds a set power threshold, it is assumed that the momentary timing value of the timing circuit () is correct and this value is stored in a non-volatile memory (), If the determined power condition gives rise to assuming malfunctioning of the timing circuit (), for example due to absence of power for a longer time, the timing circuit () is synchronised to the stored timing value.