Method of limiting charge pressure

A method of limiting a charge pressure of an internal combustion engine charged by an exhaust gas turbocharger, comprising the steps of:

• performing an actual value/setpoint value comparison of a controlled variable with a predefined limit value by a control unit;
• one of generating and limiting actuating signals from an actuator drive of an actuator acting upon the controlled variable;
• reading the limit value from a characteristic map memory as a function of an instantaneous operating state of the internal combustion engine, the limit value read in the reading step accordance with measured values of temperature and pressure upstream and downstream from a compressor of the exhaust gas turbocharger;
• setting the measured values of the temperature and the pressure in relationship to one another;
• and
• determining the limit value of the controlled variable from the characteristic map memory in accordance with a ratio of the measured values of the upstream temperature to downstream temperature and in accordance with a ratio of the measured values of the downstream pressure to the upstream pressure.