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Cogwheel sensor provides precise signal

Posted: 17 Jun 2009 ?? ?Print Version ?Bookmark and Share

Keywords:cogwheel sensor? signal? automotive?

Allegro MicroSystems is offering the ATS667LSG cogwheel sensor module with open collector output and a rotation rate range from zero to 12.000 rpm. The sensor's output signal provides an almost constant duty cyclean important aspect when it comes to cogwheel encoders in automotive transmission applications.

Sensor and magnet are integrated in one package and form a unit that is matched in terms of magnetic properties. The compact package can be used in a simple and flexible manner in a broad range of applications where cogwheel encoders are required.

The three-wire device contains two Hall elements along with the signal conditioning circuitry required to process the differential signals produced by the ferromagnetic encoder wheel. The sensor includes intelligent algorithms which reduce the magnetic system offset and handle the automatic gain control. Thus, the device provides a precise signal unaffected by the air gap width.

The signal is calibrated automatically when the device is powered up. During operation, the calibration is constantly verified. Thus, the device is not affected by vibrations and sudden variations of the air gap width.

High-resolution DACs track signal peaks. Along with the intelligent tracking algorithms, they supply the base for intelligent tracking algorithms used to implement adaptive switching thresholds. The adaptive hysteresis of these thresholds reduces negative effects by anomalies in the differential signal which are typical for encoder structures in automotive applications.

In order to improve the resilience, the device contains test structures enabling designers to verify functionality down to the transistor level.

The ATS667LSG is provided in an SG package which contains the Hall effect circuit as well as a samarium cobalt magnet. The device operates in the temperature range from -40C to 150C.

- Christoph Hammerschmidt
Automotive Design Europe

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