A control unit for the operation of a broadband lambda probe is described in German Patent Application No. DE 10 2008 001 697 A1. “Operation” encompasses in particular control of the lambda probe, as well as evaluation of the signals or data supplied by the lambda probe. The control unit encompasses a signal conditioning unit, an analog/digital (A/D) converter, a pump current controller, a digital interface, a controller, a pump current source, an internal pump electrode terminal, an external pump electrode terminal, and a reference electrode terminal. The signal conditioning unit is provided in order to ascertain an actual value for the pump current controller, and to ascertain further information regarding the operating state of the broadband lambda probe. The further information regarding the operating state of the broadband lambda probe is outputtable via the digital interface.
A corresponding control unit, in the form of an integrated circuit (IC) for controlling broadband lambda probes suitable for diesel and gasoline engines, is marketed by the Applicant under the designation “CJ135”. This control unit is described below with reference to FIG. 1.
With an aforesaid control unit, only one lambda probe of a specific probe type can respectively be controlled, evaluated, or diagnosed. For the operation of at least two lambda probes of different probe types, a corresponding number of different control units is therefore required.
In addition to the aforesaid control system for lambda probes, a plurality of further control units specialized for a particular application are encountered nowadays in internal combustion engines or in motor vehicles equipped with such internal combustion engines. An internal combustion engine is furthermore operated, in a conventional manner, by way of an engine control device. These control units or control devices possess analog and digital inputs that in part also provide additional functions such as a pull-up/pull-down structure, or a voltage divider required, for example, for the evaluation of temperature sensors. The evaluation circuits on which these are based can be made up of discrete components or, by combining multiple inputs and outputs, of individual application-specific integrated circuits (ASICs).
A separate control unit having a specific logic circuit is required for each of these different applications, so that in the event of a change in function, the hardware of the logic circuit must be adapted or an installed reserve must be provided on the respective circuit board layout.