System and method for monitoring analog front-end (AFE) circuitry of an inductive position sensor

A method for monitoring analog front-end (AFE) circuitry of an inductive position sensor,

• the method comprising:
• establishing a redundant analog front-end (AFE) channel in an inductive position sensor having an output coupled to a redundant AFE channel buffer, the AFE circuitry further comprising a sine signal AFE channel, a cosine signal AFE channel, a sine AFE channel buffer coupled to an output of the sine signal AFE channel and a cosine AFE channel buffer;
• alternately selecting a sine output signal or a cosine output signal from a receiver coil of the inductive position sensor;
• processing the sine output signal through the redundant AFE channel and the redundant AFE channel buffer when the sine output signal is selected or processing the cosine output signal through the redundant AFE channel and the redundant AFE channel buffer when the cosine output signal is selected;
• when the sine output signal is selected obtaining a voltage difference as a difference between an output voltage of the sine AFE channel buffer and an output voltage of the redundant AFE channel buffer;
• when the cosine output signal is selected, obtaining the voltage difference as the difference between an output voltage of the cosine AFE channel buffer and an output voltage of the redundant AFE channel buffer;
• determining if the obtained voltage difference is greater than a predetermined threshold voltage and if it is determined that the voltage difference is greater than the predetermined threshold voltage:
• outputting an error pulse having a duration reflective of an amount of time that the obtained voltage difference is greater than the predetermined threshold voltage;
• determining if the duration of the error pulse is greater than a predetermined error pulse filter period, and if it is determined that the duration of the error pulse is greater than the predetermined error pulse filter period:
• incrementing a fault counter;
• and
• determining if a value of the fault counter is greater than a predetermined fault counter maximum value, and if it is determined that the fault counter is greater than the predetermined fault counter maximum value, setting an output of the sine AFE channel buffer and an output of the cosine AFE channel buffer to a high impedance state.

A system for monitoring analog front-end (AFE) circuitry of an inductive position sensor,

• the system comprising:
• a redundant AFE channel;
• a redundant AFE channel buffer coupled to an output of the redundant AFE channel;
• a processor;
• and
• a comparator circuit, the processor to:
• alternately select a sine output signal or a cosine output signal from a receiver coil of an inductive position sensor;
• feed the sine output signal to the redundant AFE channel and to the redundant AFE channel buffer to process the sine output signal when the sine output signal is selected or feed the cosine output signal to the redundant AFE channel and to the redundant AFE channel buffer when the cosine output signal is selected;
• the comparator circuit to:
• obtain a voltage difference as the difference between an output voltage of a sine AFE channel buffer and an output voltage of the redundant AFE channel buffer when the sine output signal is selected;
• obtain the voltage difference as the difference between an output voltage of a cosine AFE channel buffer and the output voltage of the redundant AFE channel buffer when the cosine output signal is selected;
• determine if the voltage difference is greater than a predetermined threshold voltage;
• and
• the processor further to signal a fault condition to an electronic control unit (ECU) coupled to the inductive position sensor if it is determined that the voltage difference is greater than the predetermined threshold voltage.