Electronic fluorescent lamp ballast for discharge lamps, has end-of-life monitoring circuit and differential amplifier, where reference current along with current at which asymmetrical performance is detected is applied to amplifier

摘要

The ballast has an end-of-life monitoring circuit for detection of service life of electrodes of a discharge lamp (LA1). The monitoring circuit is activated when asymmetrical performance of the discharge lamp is detected. A current differential amplifier (U1) is provided in the monitoring circuit and a reference current along with current at which asymmetrical performance is detected is applied to the amplifier.