a and of a second partial circuit 35 b the first partial circuit 35 a is provided between the first ground line gnd 1 and the second ground line gnd 2 and upon reaching the breakdown voltage the line carries a current the second partial circuit 35 b is provided between the second ground line gnd 2 and the first ground line gnd 1 and carries current in this direction upon reaching the breakdown voltage of the zener diode 40 a in the partial circuit 35 a in other words the first partial circuit 35 a and the second partial circuit 35 b are substantially identical but are connected in reverse directions this means that the breakdown voltage in the corresponding zener diodes 40 a and 40 b in the first partial circuit 35 a and the second partial circuit 35 b can are intended to have a similar breakdown voltage should an electrostatic discharge take place either the first partial circuit 35 a or the second partial circuit 35 b can carry the current when the breakdown voltage of the corresponding zener diode 40 is reached this effect is shown in the current voltage characteristic fig4 a 4b shows a further embodiment in which a further semiconductor chip 50 is used for the esd protection circuit 30 this.