Patent ID: 7786679

Claim:
An electronic ballast for the AC operation of a discharge lamp (LA 1 ) having an EOL monitoring circuit (R 1 , R 2 , U 1 , R 9 , U 2 -A, U 2 -B, U 3 -A, AE) for detecting the end of life of the electrodes of the discharge lamp (LA 1 ), which EOL monitoring circuit (R 1 , R 2 , U 1 , R 9 , U 2 -A, U 2 -B, U 3 -A, AE) responds to an asymmetrical power of the discharge lamp (LA 1 ), characterized in that a current associated with the asymmetrical power and a reference current are fed to a current differential amplifier (U 1 ) in the EOL monitoring circuit (R 1 , R 2 , U 1 , R 9 , U 2 -A, U 2 -B, U 3 -A, AE).