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Speed sensor eliminates external switching capacitor

Posted: 22 Jun 2005 ?? ?Print Version ?Bookmark and Share

Keywords:allegro Microsystems? speed sensor? sensor? ats616lsg?

Eliminating the need for an external switching capacitor, Allegro MicroSystems Inc. has launched a new analog self-calibrating speed sensor that integrates a tracking capacitor for non-true power on-state (TPOS) camshaft applications, providing improved electromagnetic compatibility (EMC) and electrostatic discharge (ESD) protection.

The new ATS616LSG also features a smaller integrated GTS package, dubbed the SG package that includes a magnet, while maintaining the key specifications such as air gap range and high timing accuracy of the existing ATS612LSB device.

This peak-detecting device uses automatic gain control and an integrated capacitor to provide highly accurate gear-edge detection down to low operating speeds. Each sensor subassembly consists of a high-temperature plastic shell that holds together a samarium-cobalt magnet, a pole piece, and a differential open-collector Hall IC that has been optimized to the magnetic circuit. The small package can be easily assembled and used in conjunction with a wide variety of gear shapes and sizes.

The gear-sensing technology used for this sensor subassembly is Hall-effect-based. The company said the sensor incorporates a dual-element Hall IC that switches in response to differential magnetic signals created by ferrous targets, and the processing circuitry incorporates an A/D converter that self-calibrates (normalizes) the internal gain of the device to minimize the effect of air gap variations. The patented peak-detecting filter circuit is said to eliminate magnet and system offsets, and has the ability to discriminate relatively fast changes such as those caused by tilt, gear wobble, and eccentricities, yet provides stable operation to extremely low rotations per minute (RPM).

This sensor system is suitable for use in gathering speed, position and timing information using gear-tooth-based configurations, in particular for applications that require extremely accurate edge detection such as in automotive camshaft applications.

Supplied in an SG package, the ATS616LSG is priced at $2.43 in quantities of 10,000. Delivery is 22 weeks. Samples of less than 50 pieces are typically shipped within one week.

- Gina Roos


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