ELECTRONIC BALLAST WITH MULTI-SLOPE CURRENT FEEDBACK

摘要

An electronic ballast includes a multi-slope current feedback circuit comprising a current response circuit (138) responsive to lamp current and generating an adjusted lamp current signal (150), and an error circuit (134) receiving the adjusted lamp current signal (150) and a desired lamp current signal (146) to generate a lamp current error signal (148). The current response circuit (138) has a first responsiveness when the lamp current is in a low lamp current range and a second responsiveness when the lamp current is in a high lamp current range, the adjusted lamp current signal (150) being continuous between the low and the high lamp current range. The current response circuit (138) can comprises a slope altering circuit (242), a half wave rectifier (244), and an averaging circuit (246). A microprocessor can be responsive to the adjusted lamp current signal (150) and generate the desired lamp current signal (146).