Patent ID: 6476611
Filing Date: 2002-11-05
Classification: G01N

Abstract:
A circuit for monitoring and diagnosing an oxygen probe (2) provided with a sensitive cell (3) connected between a first and a second signal terminal (6, 7) and a heating member (10) connected between a battery (11) and a heating terminal (12), the circuit comprising an interface stage (15) and a control unit (16), the interface stage (15) comprising a first resistor (20) connected between a supply line (22) and the first signal terminal (6) of the oxygen probe (2), and a second resistor (23) connected between the first signal terminal (6) and the second signal terminal (7) of the oxygen probe (2), the circuit being characterized in that the control unit (16) comprises first analog-digital converter means (26) connected to the first signal terminal (6), and the second analog-digital converter means (27) connected to the second signal terminal (7) and in that the interface stage (15) comprises a third resistor (24) connected between the second signal terminal (7) and a reference potential line.