Back to results
US 8,447,556 B2Granted
Circuits and methods for generating a self-test of a magnetic field sensor
AssigneeAllegro MicroSystems, LLC
InventorsAndreas P. Friedrich, Andrea Foletto, Michael C. Doogue, William P. Taylor, Ravi Vig, P. Karl Scheller
Life of this patent
Estimating the term…
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.
Claims46
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.
1 more element
A method of generating a self-test of a magnetic field sensor, comprising:
- 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.
2 more elements
Dependencies are inferred from the claim text.