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Emerald Group Publishing Limited
Copyright © 2002, MCB UP Limited
Gear-tooth sensor module for automotive applications
Keywords: Automotive, Magnetic sensor
The ATS632LSA gear-tooth sensor module from Allegro MicroSystems Europe uses a Hall-effect sensor integrated circuit to provide extremely accurate tooth-edge detection of large-pitch targets in automotive applications (Plate 2).
Plate 2 The ATS632LSA automotive gear-tooth sensor module from Allegro MicroSystems
The sensor subassembly consists of a high- temperature plastic shell that holds together a compound samarium-cobalt magnet and a single-element self-calibrating Hail-effect IC that has been optimised to the magnetic circuit.
This small package, with its non-oriented operation, can be easily assembled on a printed-circuit board for complete protection, and can be used in conjunction with a number of gear configurations.
The sensor incorporates a single-element Hall IC that switches in response to absolute magnetic signals created by a ferrous target. The digital output is low over a tooth and high over a valley.
Self-calibrating 6-bit analogue/digital convertor circuitry adapts the thresholds to the peak-to-peak signals to minimise the effects of variation in application air gap on switch-point timing accuracy.
The effects of system and device offsets are minimised by using active offset cancellation circuitry. The digital algorithm provides zero-speed detection capabilities without the associated running jitter inherent in classical digital solutions.
This sensor system is ideal for use m gathering speed, position and profile information of ferrous objects. It is particularly suited to use in large tooth/valley sensing applications where accurate timing accuracy is a desired feature.
Allegro MicroSystems Europe Ltd, Balfour House, Churchfield Road, Walton-on- Thames, Surrey, KT12 2TD, UK. Tel: +33 (0)4 50512359; Fax: +33 (0) 4 50512083; E-mail: email@example.com; Web site: http://www. allegromicro.com