Allegro Microsystems, LLC

Aisin Seiki Kabushiki Kaisha

Karl Scheller

Ravi Vig

Devon Fernandez

Cory Voisine

Kirsten Doogue

Gerardo A Monreal

Jay M Towne

Jason Stauth

Glenn A Forrest

Kazuhiro Kamiya

Takayoshi Tsuzuki

Kenichi Taguchi

Takashi Hara

Toshiyuki Matsuo

Jeff Eagen

Apparatus and methods for detecting passing magnetic articles using a first, True Power On State (TPOS) detector during a first time interval and transitioning to a second, running mode detector after the first time interval, when the output of the second detector is accurate. A phase comparator is responsive to the output signal of the first and second detectors and provides a control signal indicative of a change in the phase relationship between the two output signals. An output switch controlled by the phase comparator provides, as the detector output signal, the first detector output signal during the first time interval and the second detector output signal thereafter. A threshold signal associated with the TPOS detector is at a fixed level during a first portion of the first time interval and is adjusted during a second portion of the first time interval in response to an automatic gain control circuit in order to reduce the phase error associated with transitioning from the TPOS detector to the running mode detector. Also described are apparatus and methods for updating a running mode threshold signal that is a percentage of the peak-to-peak magnetic field sensor signal, so that unnecessary update events are reduced.

Methods and apparatus for magnetic article detection

A track-and-hold peak detector circuit, which can operate at low input signal frequencies, includes a capacitor to hold a peak voltage of the input signal and logic circuitry that reduces an effect of leakage current into or out of the capacitor, and therefore, provides protection against self-switching of an output signal of the peak detector circuit.

Track-and-hold peak detector circuit

A proximity detector includes a fine DAC and a coarse DAC, outputs of which are summed to provide a tracking signal for tracking a magnetic field signal. The proximity detector provides two mode of operation. In a first mode of operation the coarse and fine DACs operate in combination as one higher order DAC. In a second mode of operation, the coarse DAC is provided with one or more extra counts, allowing the tracking signal to move more rapidly to track a rapidly changing magnetic field signal. In another embodiment, the proximity detector also includes an offset circuit for bringing at least one of the magnetic field signal and the tracking signal towards the other one of the magnetic field signal and the tracking signal.

Proximity detector

Disclosed is a rotation detecting sensor suitable for use under a vibration-abundant condition as e.g. a sensor disposed in an automobile body for detecting rotation of an engine or ABS. The sensor includes a detecting element for detecting rotation of a rotary body as a change in a magnetic flux and outputting a signal and an integrated circuit for processing the amplified signal into a pulse corresponding to the detected rotation of the rotary body. The signal processing includes an initialization such as a gain adjustment for obtaining an appropriate gain for use in the subsequent process of conversion of the amplified signal to the pulse. According to this invention, a re-initialization is effected to obtain a new initial value such as a new gain if the previously effected initialization is determined inappropriate.

Rotation detecting sensor

Growing community of inventors

Bow, NH, United States of America

Karl Scheller