Semiconductor light emitting element drive device and lighting fixture with the same

摘要

A semiconductor light emitting element drive device (10) includes: a converter circuit (5) configured to supply a light source unit (9) with a load current from a first-primary winding (N1) connected to a first switching device (Q1); and a current regulation circuit (6). The converter circuit (5) further includes a first- and second-secondary windings (N2, N3). The current regulation circuit (6) includes a second switching device (Q2) connected in series with the second-secondary winding (N3). In a dimming ratio of the light source unit (9) is lower than a first ratio, the second switching device (Q2) is controlled to ON and OFF so as to decrease the load current through the light source unit (9) by a shunt of a part of the energy stored in the primary winding (N1).