IC-based low cost reliable electronic ballast with multiple striking attempts and end of lamp life protection

摘要

The present invention relates generally to a simple, low cost ballast for fluorescent lamps that incorporates an integrated circuit and a number of ballast protection functions to cost effectively enhance its reliability. End of lamp life circuitry is provided to shut down the ballast when rectification currents due to lamp aging exceed a predetermined level. This circuitry also functions to stop the ballast operation when the lamp's voltage exceeds a predetermined cutoff level for a set period of time. Re-ignition circuitry is provided that restarts the ballast when new lamps are installed without shutting off the ballast. Multiple striking attempt circuitry is provided that initiates a predetermined number of striking attempts such that cold or old lamps are quickly ignited without the introduction of excessive flickering.