Dimmer control circuit for selecting between step dimming mode and phase-cut dimming mode

摘要

The present invention relates to a dimmer control circuit (100) capable to detect whether a phase-cut dimmer is connected using an average signal (VDCI) derived from the mains voltage. The average signal (VDCI) or a signal (VDCI_ls) derived from (VDCI), ranging from a minimum value to a maximum value, is compared to a dimming threshold (Vdim_th) through a phase-cut detecting unit (20). The comparison result is used to control the state diagram of a dimmer control logic (40) by selecting the step dimming mode (STD) or the phase-cut dimming mode (PCD). The output (OUT) of a switching unit (30) is determined by the state diagram of the dimmer control logic (40) in such a manner that the phase-cut dimming mode (PCD) is prioritized above the step-dimming mode (STD) and the maximum level of the STD states is depending on the mains voltage and application adjustable.