The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 22, 2008
Filed:
Jan. 17, 2006
Cory Voisine, Weare, NH (US);
Devon Fernandez, Manchester, NH (US);
Karl Scheller, Bow, NH (US);
Ravi Vig, Bow, NH (US);
Kirsten Doogue, Manchester, NH (US);
Cory Voisine, Weare, NH (US);
Devon Fernandez, Manchester, NH (US);
Karl Scheller, Bow, NH (US);
Ravi Vig, Bow, NH (US);
Kirsten Doogue, Manchester, NH (US);
Allegro Microsystems, Inc., Worcester, MA (US);
Abstract
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.