Reference voltage diagnostic suitable for use in an automobile controller and method therefor
First Claim
1. A diagnostic apparatus suitable for use in an automobile controller comprising:
- a power supply terminal conducting a reference voltage;
a sampling circuit coupled to said power supply terminal and having an output terminal for providing sampled values of said reference voltage; and
a reference voltage diagnostic circuit having an input terminal coupled to said output terminal of said sampling circuit, wherein said reference voltage diagnostic circuit maintains a historical value of said reference voltage over a predetermined time period, compares a current sampled value of said reference voltage to said historical value, and indicates a fault in said reference voltage in response to said current sampled value being different from said historical value by more than a predetermined threshold.
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Accused Products
Abstract
A diagnostic apparatus is suitable for use in an automobile controller and includes a power supply terminal conducting a reference voltage, a sampling circuit and a reference voltage diagnostic circuit. The sampling circuit is coupled to the power supply terminal and has an output terminal for providing sampled values of the reference voltage. The reference voltage diagnostic circuit has an input terminal coupled to the output terminal of the sampling circuit. The reference voltage diagnostic circuit maintains a historical value of the reference voltage over a predetermined time period, compares a current sampled value of the reference voltage to the historical value, and indicates a fault in the reference voltage in response to the current sampled value being different from the historical value by more than a predetermined threshold.
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Citations
20 Claims
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1. A diagnostic apparatus suitable for use in an automobile controller comprising:
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a power supply terminal conducting a reference voltage;
a sampling circuit coupled to said power supply terminal and having an output terminal for providing sampled values of said reference voltage; and
a reference voltage diagnostic circuit having an input terminal coupled to said output terminal of said sampling circuit, wherein said reference voltage diagnostic circuit maintains a historical value of said reference voltage over a predetermined time period, compares a current sampled value of said reference voltage to said historical value, and indicates a fault in said reference voltage in response to said current sampled value being different from said historical value by more than a predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 12)
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8. A diagnostic apparatus suitable for use in an automobile controller comprising:
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first and second power supply terminals respectively conducting first and second reference voltages;
a sampling circuit coupled to said first and second power supply terminals and having an output terminal for providing sampled values of said first and second reference voltages; and
a reference voltage diagnostic circuit having an input terminal coupled to said output terminal of said sampling circuit, wherein said reference voltage diagnostic circuit compares a sampled value of said first reference voltage to a sampled value of said second reference voltage, and indicates a fault in at least one of said first and second reference voltages in response a difference between said sampled value of said first reference voltage and said sampled value of said second reference voltage being greater than a predetermined threshold. - View Dependent Claims (9, 10, 11)
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13. A method of diagnosing a fault of a reference voltage in an automobile controller or the like, comprising the steps of:
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determining a current value of said reference voltage;
comparing said current value of said reference voltage to a historical value of said reference voltage; and
indicating a fault in said reference voltage if said current value is not within a predetermined threshold of the historical value. - View Dependent Claims (14, 15, 16, 17)
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18. A method of diagnosing a fault in one of multiple reference voltages in an automobile controller or the like, comprising the steps of:
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determining values of first and second reference voltages;
calculating a difference between said first reference voltage and said second reference voltage;
comparing said difference to a predetermined threshold; and
indicating a fault in one of said first and second reference voltages if said difference is greater than said predetermined threshold. - View Dependent Claims (19, 20)
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Specification