Allegro Microsystems, LLC

Florian Kulla

Andrea Foletto

Yannick Vuillermet

Cédric Gillet

Methods and apparatus for an orientation insensitive speed sensor. Magnetic field sensing elements can be located on a circle, for example, to generate first and second channel signals which can be combined to generate an output signal. The location of the magnetic field sensing elements reduces the effects of stray fields. Embodiments can include true power own state processing to determine target position during start up.

Orientation independent magnetic field sensor

A magnetic field sensor for detecting motion of an object includes one or more magnetic field sensing elements configured to generate a magnetic field signal in response to a magnetic field associated with the object and a detector configured to generate a comparison signal having edges occurring in response to a comparison of the magnetic field signal and a threshold signal and occurring at a rate corresponding to a speed of motion of the object. A speed monitor responsive to the comparison signal is configured to generate a speed signal having a value indicative of the speed of motion of the object. A threshold generator having an input coupled to receive the speed signal from the speed monitor and an output coupled to the detector is configured to generate the threshold signal at a first level when the value of the speed signal indicates that the speed of motion of the object is greater than a predetermined speed and at a second level when the value of the speed signal indicates that the speed of motion of the object is less than the predetermined speed.

Magnetic field sensor with an adjustable threshold for stray field immunity

A magnetic field sensor includes at least one magnetic field sensing element configured to generate a magnetic field signal indicative of a magnetic field associated with a target, an analog-to-digital converter configured to convert the magnetic field signal into a digital magnetic field signal, and a controller responsive to the digital magnetic field signal and configured to adjust an offset of the digital magnetic field signal during a first operational phase and to increase a gain of the digital magnetic field signal during a second operational phase following the first operational phase. The first and second operational phases occur during a running mode of sensor operation.

Magnetic field sensor offset and gain adjustment

A magnetic field sensor including at least one magnetoresistance element configured to generate a magnetic field signal indicative of a magnetic field associated with a target having features and spaced from the at least one magnetoresistance element by an airgap. The sensor includes a detector responsive to the magnetic field signal and to a threshold level to generate a sensor output signal containing transitions, each transition associated with a feature of the target and occurring in response to the magnetic field signal crossing the threshold level. The sensor includes a threshold generator configured to generate the threshold level having a rising threshold level limit and a falling threshold level limit.

Magnetic field sensor with threshold level limits and associated methods

A magnetic field sensor including at least one magnetic field sensing element configured to generate a magnetic field signal indicative of a magnetic field associated with a target and a detector responsive to the magnetic field signal and to a threshold level to generate a sensor output signal containing transitions associated with features of the target in response to the magnetic field signal crossing the threshold level further includes a threshold generator to generate an adaptive threshold. The threshold generator is configured to generate the threshold level to achieve a predetermined fixed hard offset and that adapts with a variation in the airgap in order to minimize an error between times or angles of the transitions of the sensor output signal over the variation in the airgap.

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Annecy, France

Florian Kulla