A Universal dimmer which alternates between leading and trailing edge mode dependent upon detection of an inductive load

摘要

Disclosed is a universal dimmer for controlling power applied to a load. The dimmer operates in a trailing edge mode upon activation and includes: a load type detector for detecting a load type upon activation of the dimmer. The load type detector includes an inductive load detector for detecting the presence of an inductive load, the inductive load detector including a voltage ringing detector for detecting a voltage ringing signal across the load. The voltage ringing detector includes: a filter for extracting a voltage ringing signal and filtering out a line voltage frequency in a signal across the inductive load; a peak detector for detecting peaks in the voltage ringing signal; and a mode control circuit to change the operation of the universal dimmer to leading edge mode if an inductive load is detected by the load type detector.