Circuits and methods for generating a self-test of a magnetic field sensor
First Claim
Patent Images
1. A magnetic field sensor, comprising:
- a magnetic field sensing element supported by a substrate, the magnetic field sensing element for generating a composite magnetic field signal comprising a measured-magnetic-field-responsive signal portion and a self-test-responsive signal portion, wherein the measured-magnetic-field-responsive signal portion is responsive to a measured magnetic field and the self-test-responsive signal portion is responsive to a self-test magnetic field;
a self-test circuit comprising a self-test current conductor proximate to the magnetic field sensing element, the self-test current conductor for carrying a self-test current to generate the self-test magnetic field, wherein the self-test circuit further comprises a diagnostic request processor configured to control the self test current to be on or off in response to a diagnostic input signal received by the diagnostic request processor or to be indicative of a self test during one or more time periods in response to a control signal generated by the diagnostic request processor; and
a processing circuit coupled to receive a signal representative of the composite magnetic field signal, configured to generate a sensor signal representative of the measured-magnetic field-responsive signal portion, and configured to generate at least one of a diagnostic signal representative of the self-test-responsive signal portion or a composite signal representative of both the measured-magnetic-field-responsive signal portion and the self-test-responsive signal portion.
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Abstract
A magnetic field sensor includes built in self-test circuits that allow a self-test of most of, or all of, the circuitry of the magnetic field sensor, including self-test of a magnetic field sensing element used within the magnetic field sensor, while the magnetic field sensor is functioning in normal operation.
146 Citations
46 Claims
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1. A magnetic field sensor, comprising:
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a magnetic field sensing element supported by a substrate, the magnetic field sensing element for generating a composite magnetic field signal comprising a measured-magnetic-field-responsive signal portion and a self-test-responsive signal portion, wherein the measured-magnetic-field-responsive signal portion is responsive to a measured magnetic field and the self-test-responsive signal portion is responsive to a self-test magnetic field; a self-test circuit comprising a self-test current conductor proximate to the magnetic field sensing element, the self-test current conductor for carrying a self-test current to generate the self-test magnetic field, wherein the self-test circuit further comprises a diagnostic request processor configured to control the self test current to be on or off in response to a diagnostic input signal received by the diagnostic request processor or to be indicative of a self test during one or more time periods in response to a control signal generated by the diagnostic request processor; and a processing circuit coupled to receive a signal representative of the composite magnetic field signal, configured to generate a sensor signal representative of the measured-magnetic field-responsive signal portion, and configured to generate at least one of a diagnostic signal representative of the self-test-responsive signal portion or a composite signal representative of both the measured-magnetic-field-responsive signal portion and the self-test-responsive signal portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 43, 44)
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37. A method of generating a self-test of a magnetic field sensor, comprising:
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generating, with a magnetic field sensing element, a composite magnetic field signal comprising a measured-magnetic-field-responsive signal portion and a self-test-responsive signal portion, wherein the measured-magnetic-field-responsive signal portion is responsive to a measured magnetic field and the self-test-responsive signal portion is responsive to a self-test magnetic field; controlling a self-test current in a self-test current conductor proximate to the magnetic field sensing element to be on or off in response to a diagnostic input signal received by the diagnostic request processor or to be indicative of as self test during one or more time periods in response to a control signal generated by the diagnostic request processor, the self-test current conductor for carrying the self-test current to generate the self-test magnetic field; generating a sensor output signal representative of the measured-magnetic-field-responsive signal portion; and generating at least one of a diagnostic signal representative of the self-test-responsive signal portion or a composite signal representative of both the measured-magnetic-field-responsive signal portion and the self-test-responsive signal portion. - View Dependent Claims (38, 39, 40, 41, 42, 45, 46)
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Specification