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Allegro MicroSystems, Inc. Introduces True Zero-Speed
Digital Speed Sensor
ATS642LSH includes running mode calibration 
Worcester, MA, November 3, 2005 — Allegro MicroSystems, Inc. announces an innovative addition to its cutting-edge speed-sensing solutions, the ATS642LSH. This sensor IC addresses critical requirements specific to ABS speed-sensing applications. In particular, the sensitive ATS642 achieves far airgap requirements, as well as incorporates algorithms that eliminate the chance for false learning due to calibration on micro-vibrations at start-up. Additionally, the ATS642 is able to handle extreme airgap variations due to cornering events.
The ATS642 device is a two-wire, dual-element, Hall-effect sensor IC that switches in response to differential magnetic signals from a ferrous target.
The ATS642 centers the internally processed differential signal at power-up. It then immediately begins to track the differential signal and enters into the calibration phase. During calibration, the device effectively watches the amplitude of the signal. If the amplitude is sufficiently large, it reduces the gain to an optimal setting and centers the signal if required to maintain optimum switching. The ATS642 continues to monitor the signal and, once amplitude has been optimized, enters into running mode operation.
During running mode, the device follows the differential signal and looks for three consecutive peaks out of range. As such it assumes that it has miscalibrated, potentially on target micro-vibration. Should this event occur, the device will adjust the gain accordingly and, if necessary, readjust the signal to compensate for any offset. This is all accomplished without missing a transition and while keeping very tight duty cycle over speed and temperature. Furthermore, this algorithm makes the ATS642 relatively immune to micro-vibrations during start-up.
This sensor system is ideal for use in anti-lock braking systems and two-wire industrial speed sensor applications.
About Allegro
Allegro MicroSystems, Inc. is a leader in developing, manufacturing and marketing high-performance power and Hall-effect sensor integrated circuits. Allegro's innovative solutions serve high-growth applications within the automotive, communications, computer/office automation, consumer and industrial markets. Allegro is headquartered in Worcester, Massachusetts (USA) with design and applications centers located in North and South America, Asia, and Europe. Further information about Allegro can be found at www.allegromicro.com.
Editorial Contact:
Stephanie Fennelly
Director - Marketing Communications
Tel: (508) 854-5363
sfennelly@allegromicro.com