Magnetic field sensors with self test
AssigneeAllegro MicroSystems, LLC
InventorsCraig S. Petrie, Bryan Cadugan, David Toebes, Michael C. Doogue, William P. Taylor
Life of this patent
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Abstract
A system includes a magnetic target and a magnetic field sensor. The magnetic field sensor comprises an output node; a circuit to detect a magnetic field produced by the magnetic target; and a processor. The processor may be configured to transmit a signal onto the output node representing the detected magnetic field; detect whether the transmitted signal is interrupted by an external source; and, if the signal is interrupted, initiate a self-test of the apparatus. Corresponding methods and apparatuses are also disclosed.
Claims31
A method comprising:
- detecting, by a magnetic field sensor, a magnetic field;
- driving a signal representing the magnetic field onto an output node of the magnetic field sensor;
- receiving, by the magnetic field sensor, the signal on the output node;
- determining if the driven signal is interrupted by an external source by comparing the received signal to the driven signal by determining if a voltage of the output node was driven to a predetermined voltage state during transmission of the signal representing the magnetic field;
- interrupting the signal representing the magnetic field and
- when the driven signal is interrupted, initiating a self-test.
An apparatus comprising:
- an output node;
- a circuit to detect a magnetic field;
- a processor circuit configured to:
- transmit a signal representing the detected magnetic field onto the output node;
- detect whether the transmitted signal is interrupted by an external source by sensing whether the output node is held at a low voltage by the external source;
- and
- if the signal is interrupted, initiate a self-test of the apparatus.
A system comprising
- a magnetic target;
- a magnetic field sensor comprising:
- an output node;
- a circuit to detect a magnetic field produced by the magnetic target;
- and
- a processor circuit configured to:
- transmit a signal representing the magnetic field onto the output node;
- detect whether the transmitted signal is interrupted by an external source by sensing whether the output node is held at a low voltage by the external source;
- and
- if the signal is interrupted, initiate a self-test of the apparatus.
An apparatus comprising:
- an output node;
- a circuit to detect a magnetic field;
- a processor circuit configured to:
- transmit a signal representing the detected magnetic field onto the output node;
- detect whether the transmitted signal is interrupted by an external source by sensing whether the output node is held at a low voltage by an external source;
- if the signal is interrupted, initiate a self-test of the apparatus;
- and
- transmit data representing test results onto the output node if results of the self-test indicate a failure.
An apparatus comprising:
- an output node;
- a circuit to detect a magnetic field;
- a processor circuit configured to:
- transmit a signal representing the detected magnetic field onto the output node;
- detect whether the transmitted signal is interrupted by an external trigger signal;
- if the signal is interrupted, initiate a self-test of the apparatus;
- and
- transmit data representing test results onto the output node if results of the self-test indicate a failure.
Dependencies are inferred from the claim text.