US 5,493,214 A · Fault detection scheme for a variable reluctance sensor interface having a differential input and adaptive control

Abstract

In accordance with the teachings of the present invention, a fault detection circuit is provided which detects short circuits on differential leads associated with a magnetic sensor and modifies said differential voltage to avoid possible errors associated with a short circuit. The circuit includes a first and second input coupled to first and second signal lines for receiving a differential voltage. A first voltage comparator compares voltage potentials at the first and second signal lines so as to detect equal voltage crossings and provide an output in response thereto. A rectifier is coupled to the first and second signal lines in the output of the first comparator and has first and second outputs for producing positive half-wave voltage cycles with a voltage potential at each of the first and second lead lines. A second comparator is provided for comparing the half-wave voltage cycles with a first threshold voltage that represents a short circuit power source. A third comparator is provided for comparing the half-wave voltage cycles with a second threshold voltage that represents a short circuit to ground. The voltage potentials at the first and second signal lines are converted to separate single-ended voltages when one of the second and third voltage comparators detects a short circuit so as to correct for possible errors caused by the short circuit.

Claims16

Dependent claims

A fault detection circuit for detecting short circuiting faults along signal lines associated with a magnetic sensor which produces an alternating differential voltage in response to rotation of a wheel, comprising:

first and second signal lines coupled to said sensor for receiving said differential voltage;
a first voltage comparator for comparing voltage potentials at said first and second signal lines so as to detect equal voltage crossings and providing an output in response thereto;
rectification means coupled to said first and second signal lines and the output of said first comparator and having first and second outputs for producing positive half-wave voltage cycles for the voltage potential at each of said first and second signal lines;
a second comparator for comparing the half-wave voltage cycles with a first threshold voltage that represents a short circuit to a power source;
a third comparator for comparing the half-wave voltage cycles with a second threshold voltage that represents a short circuit to ground;
and
means for converting the voltage potential at said first and second signal lines to separate single-ended voltages when one of said second and third voltage comparators detects a short circuit.

4 more elements

An apparatus for developing a series of voltage pulses that are developed during rotation of a wheel comprising:

a magnetic sensor associated with said wheel having a pick-up coil and means for causing an alternating differential voltage to be generated in said pick-up coil when said wheel rotates relative to said sensor;
an input circuit having first and second signal lines coupled to said pick-up coil for receiving said differential voltage and an adaptive loading network coupled between said first and second signal lines;
rectification means coupled to said first and second signal lines and having first and second outputs for producing positive half-wave voltage cycles for the voltage potentials at each of said first and second signal lines;
a first voltage comparator for comparing the half-wave voltage cycles with a first threshold voltage potential to a first threshold voltage that represents a short circuit to a power source;
a second voltage comparator for comparing the half-wave voltage cycles with a second threshold voltage that represents a short circuit to ground;
means for converting the voltage potential at the first and second signal lines to separate single-ended voltages when one of said first and second voltage comparators detects a short circuit;
and
an output circuit for producing said series of voltage pulses from said differential voltage.

5 more elements

Dependencies are inferred from the claim text.

Fault detection scheme for a variable reluctance sensor interface having a differential input and adaptive control

Life of this patent

Fault detection scheme for a variable reluctance sensor interface having a differential input and adaptive control

Life of this patent

Abstract

Claims16