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US 8,818,749 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
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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.
Claims22
A magnetic field sensor, comprising:
- a magnetic field sensing element supported by a substrate, wherein the magnetic field sensing element is configured to generate a self-test signal responsive to a pulsing self-test magnetic field during one or more self-test time periods;
- a self-test circuit supported by the substrate, the 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;
- a processing circuit coupled to receive a signal representative of the self-test signal;
- and
- 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 diagnostic clock signal generated by the diagnostic request processor, wherein the diagnostic request processor comprises at least one of:
- a decoder coupled to receive the diagnostic input signal, configured to decode the diagnostic input signal, and configured to generate a decoded diagnostic signal, or
- an internal diagnostic clock generator configured to generate the diagnostic clock signal to control the self-test current to comprise a group of current pulses during the one or more time periods, wherein,
- the diagnostic request processor is configured to generate the diagnostic control signal to control the self-test current in response to at least one of the decoded diagnostic signal or the diagnostic clock signal.
6 more elements
A method of generating a self-test of a magnetic field sensor, comprising:
- generating, with a magnetic field sensing element supported by a substrate, a self-test signal responsive to a pulsing self-test magnetic field during one or more self-test time periods;
- providing a self-test circuit supported by the substrate, the providing the self-test circuit comprising:
- providing 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;
- providing a processing circuit coupled to receive a signal representative of the self-test signal;
- and
- providing 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 diagnostic clock signal generated by the diagnostic request processor, wherein the diagnositc request processor comprises at least one of:
- a decoder coupled to receive the diagnostic input signal, configured to decode the diagnostic input signal, and configured to generate a decoded diagnostic signal, or
- an internal diagnostic clock generator configured to generate the diagnostic clock signal to control the self-test current to comrprise a group of current pulses during the one or more time periods, wherein,
- the diagnostic reguest processor is configured to generate the diagnostic control signal to control the self-test current in response to at least one of the decoded diagnostic signal or the diagnostic clock signal.
6 more elements
Dependencies are inferred from the claim text.