Analog Devices International Unlimited Company

Michael Mueller-Aulmann

Jochen Schmitt

Aude Richard

Jan Kubik

John O'Dowd

Stephen O'Brien

Peter James Tonge

Monsoon Dutt

Robert Guyol

Enda Joseph Nicholl

Brian O'Mara

Wenmei Wang

Colin P Giles

Christian Nau

A magnetic sensor package comprising a magnetic multi-turn sensor die and a magnetic single turn sensor die, in which both sensor dies are packaged on the same lead frame. A method of manufacturing the magnetic sensor package is also provided. A magnetic sensor system comprising a rotating magnet and the magnetic sensor package, where the sensor package is arranged so that both sensor dies sit within a homogenous magnetic field, thereby ensuring that the output signal of each sensor is not corrupted by any stray fields.

Magnetic sensor package and magnetic sensing system

The present disclosure provides magnetic sensor system that includes a magnet mounted on the end of a rotating shaft, a magnetic sensing device comprising a magnetic multi-turn sensor, and a mechanism for initializing the magnetic multi-turn sensor into a known state ready for use. Whilst the magnetic sensing device is being used to monitor the rotation of the shaft, the magnet is located in a starting position a first distance from the magnet sensing device such that the magnet field strength experienced by the magnet sensing device is within the operating window of the magnet multi-turn sensor, the operating window being defined by a minimum magnetic flux density, Bmin, and a maximum magnetic flux density, Bmax. The mechanism comprises a means for moving the magnet and the shaft in an axial direction towards the magnet sensing device such that the magnetic field experienced by the magnet sensing device exceeds the upper limit, Bmax, of the operating window. This causes domain wall nucleation, whereby the sensor spiral is filled with domain walls that magnetise all of the magnetoresistive elements into the same state. Once the initialization has taken place, the mechanism is configured to return the magnet to its starting position ready for use. In this respect, the mechanism may have a biasing means such as a spring that biases the magnet towards the starting position.

Magnetic sensor system with initialization mechanism

Magnetic sensor package

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NiedererBach, Germany

Michael Mueller-Aulmann