Interference-immune position sensors

Lives depend on the safe operation of the brake pedal in a car or the arm of a surgical robot. Innovation from ams ensures that their position sensors can be relied on – in all conditions.

The Hall magnetic sensor has been used in electronics systems for decades. The first applications for Hall sensors provided basic functionality, such as switching. When you close the lid of your laptop computer, for instance, it is normally a Hall switch which detects this, so the display can automatically turn off to save power.

But in the 21st century, the technology of Hall sensors has become steadily more sophisticated. Today’s Hall-based position sensors can measure very precisely the angle of rotation of electric motors or of a vehicle’s steering wheel. In products developed here at ams, an entire rotary position sensor is integrated in a single silicon chip: from the Hall sensor array, to the signal conditioning which amplifies the tiny signal from the sensor elements, to the powerful processor which converts the magnetic measurements into position co-ordinates.

A mission-critical component

As these sensor devices have become more and more sophisticated and capable, their role in electronics systems has become more crucial. In fact, in many automotive and industrial systems, lives depend on the position sensors which we make at ams. There is little room for error in the magnetic sensor which measures how far the driver has turned the steering wheel of a car, or which tracks the position of the arm of a medical robot performing open heart surgery. Just as important, the sensor cannot be allowed to unexpectedly fail or malfunction.

There is a lot riding on the position sensor in these applications – and on the company which manufactures it. Fortunately for our customers, ams has many years of experience in supplying mission-critical position sensors, and helping manufacturers build in safety from the ground up.

For a decade and a half, ams has been supplying magnetic position sensors all over the world: we have shipped more than 750 million high-performance position sensors, for use in cars and other vehicles, and in industrial products such as motors. In the use cases we support, failure is not an option. And that’s why all our position sensors offer a unique and very special feature: differential sensing technology.

Steering clear of interference

Whether in a car or in a factory, magnetic position sensors are exposed to strong magnetic interference, induced by motors, solenoids, high-voltage cables, and other sources. The unique differential sensing architecture invented by ams provides inherent immunity to these so called ‘stray magnetic fields.’  Even in the traction motor driving the wheels of an electric vehicle – one of the most magnetically complex environments you could imagine – this immunity means that an ams position sensor continuously produces accurate angle measurements, unaffected by distortion or delay.  

Inherent immunity to stray magnetic fields is a feature of all ams position sensors, including those used in an electric vehicle’s high-speed electric motors, and in other applications requiring measurement of complete 360° rotations.

We have also developed other ways to make our products ultra-reliable. Dual-die position sensors offer fully redundant operation. Self-diagnosis and system check functions ensure the sensor is working properly at start-up and in operation. Features such as these help our automotive customers to comply with ISO 26262, a crucial industry standard for validating the safety of electronics systems in vehicles.

ISO 26262 compliance is just one of the ways in which we have gone beyond conventional position sensor products to meet the special needs of the automotive and industrial markets. Today, ams provides the industry’s most advanced and application-ready portfolio of magnetic position sensors for motor control and other mission-critical functions.

The sophistication of these integrated sensor devices from ams is a far cry from the basic Hall switches of the 20th century. Innovation from ams has led the way, and OEMs in the industrial and automotive markets can continue to rely on ams to meet their applications’ needs.

Find out more information on ams’ stray field immunity technology