Patent ID: 7420334

Claim:
An electronic ballast for a lamp having a bridge circuit, which comprises at least one first switch (S 1 ) and a second switch (S 2 ) which are coupled between a connection (A 1 ) for a supply voltage and a connection (A 2 ) for a ground potential, a center point (M) of the bridge circuit being defined between the first switch (S 1 ) and the second switch (S 2 ); a first connection (A 1 ) and a second connection (A 2 ) for a lamp (La), the first connection (A 1 ) being coupled to the center point (M) of the bridge circuit via an inductance (L 1 ); and a signal evaluation unit ( 20 ), the signal evaluation unit ( 20 ) comprising a first input ( 24 ) and a second input ( 22 ), the first input ( 24 ) being coupled to a signal which is at the DC voltage level of the first connection (A 1 ) for the lamp (La), and the second input ( 22 ) being coupled to a signal which is at the DC voltage level of the second connection (A 2 ) for the lamp (La), characterized in that the DC voltage reference potential for the signal evaluation unit ( 20 ) is designed to be variable within a value range which is greater than or equal to the ground potential and is less than or equal to the supply voltage potential.