| 摘要 |
A circuit arrangement for operating a linear exhaust-gas probe has a measuring cell for measuring a gas concentration by determining a measuring-cell voltage, in addition to a pump cell for pumping gas. A comparator circuit compares the measuring-cell voltage with a target voltage and provides a corresponding analog deviation signal. A pump current source provides the pump current is controlled by the deviation signal using a control circuit for the approximation of the measuring cell voltage to the target voltage. In order to reliably limit the pump voltage with no significant detrimental effect on the operation, the circuit also comprises: a second comparator circuit for comparing the pump voltage with a predefined threshold voltage and for providing a corresponding binary switching signal; and a counter coupling path between the output of the pump current source and the control circuit, the path being enabled when the threshold voltage is exceeded.
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