Circuits and methods for generating a diagnostic mode of operation in a magnetic field sensor
First Claim
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1. A magnetic field sensor, comprising:
- at least two magnetic field sensing elements; and
a switching circuit coupled to the at least two magnetic field sensing elements, wherein the switching circuit is configured to couple the at least two magnetic field sensing elements into a normal mode configuration when the magnetic field sensor is in a normal mode of operation, and wherein the switching circuit is configured to couple the at least two magnetic field sensing elements into a diagnostic mode configuration when the magnetic field sensor is in a diagnostic mode of operation, wherein the switching circuit is configured to couple the at least two magnetic field sensing elements in parallel so as to respond in cooperation in the presence of an external magnetic field when coupled in the normal mode configuration, and to couple the at least two magnetic field sensing elements such that the responses to the external magnetic field oppose one another when coupled in the diagnostic mode configuration, and wherein the at least two magnetic field sensing elements are configured to generate a magnetic field signal comprising;
a measured-magnetic-field-responsive signal portion responsive to the external magnetic field and substantially unresponsive to a diagnostic magnetic field when coupled in the normal mode configuration; and
a diagnostic-magnetic-field-responsive signal portion responsive to the diagnostic magnetic field and substantially unresponsive to the external magnetic field when coupled in the diagnostic mode configuration.
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Abstract
A magnetic field sensor includes a diagnostic circuit that allows a self-test of most of or all of, the circuitry of the magnetic field sensor, including a self-test of a magnetic field sensing element used within the magnetic field sensor. The magnetic field sensor can generate a diagnostic magnetic field to which the magnetic field sensor is responsive.
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Citations
23 Claims
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1. A magnetic field sensor, comprising:
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at least two magnetic field sensing elements; and a switching circuit coupled to the at least two magnetic field sensing elements, wherein the switching circuit is configured to couple the at least two magnetic field sensing elements into a normal mode configuration when the magnetic field sensor is in a normal mode of operation, and wherein the switching circuit is configured to couple the at least two magnetic field sensing elements into a diagnostic mode configuration when the magnetic field sensor is in a diagnostic mode of operation, wherein the switching circuit is configured to couple the at least two magnetic field sensing elements in parallel so as to respond in cooperation in the presence of an external magnetic field when coupled in the normal mode configuration, and to couple the at least two magnetic field sensing elements such that the responses to the external magnetic field oppose one another when coupled in the diagnostic mode configuration, and wherein the at least two magnetic field sensing elements are configured to generate a magnetic field signal comprising; a measured-magnetic-field-responsive signal portion responsive to the external magnetic field and substantially unresponsive to a diagnostic magnetic field when coupled in the normal mode configuration; and a diagnostic-magnetic-field-responsive signal portion responsive to the diagnostic magnetic field and substantially unresponsive to the external magnetic field when coupled in the diagnostic mode configuration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of generating a self-test of a magnetic field sensor, comprising:
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coupling at least two magnetic field sensing elements into a normal mode configuration when the magnetic field sensor is in a normal mode of operation, wherein the coupling the at least two magnetic field sensing elements into the normal mode configuration comprises coupling the at least two magnetic field sensing elements in parallel so as to respond in cooperation in the presence of an external magnetic field, and coupling the at least two magnetic field sensing elements into a diagnostic mode configuration when the magnetic field sensor is in a diagnostic mode of operation, and wherein the coupling the at least two magnetic field sensing elements into the diagnostic mode configuration comprises coupling the at least two magnetic field sensing elements such that their responses to the external magnetic field oppose one another, wherein the at least two magnetic field sensing elements are configured to generate a magnetic field signal comprising; a measured-magnetic-field-responsive signal portion responsive to the external magnetic field and substantially unresponsive to a diagnostic magnetic field when coupled in the normal mode configuration; and a diagnostic-magnetic-field-responsive signal portion responsive to the diagnostic magnetic field and substantially unresponsive to the external magnetic field when coupled in the diagnostic mode configuration. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification