Sentron Ag

Landis & Gyr Betriebs Ag

Jan Hrejsa

Radivoje Popovic

Robert Racz

Hubert Blanchard

A magnetic field sensor has two flux concentrators which serve to strengthen a magnetic field to be measured and which are separated by an air gap. Two Hall elements are arranged outside the air gap in such a way that at least a part of the field lines which lead from the first to the second flux concentrator pass through the two Hall elements in approximately opposite directions. Such a magnetic field sensor is less sensitive to external interference fields. It is suitable for the measurement of very weak magnetic fields and also for use as a current and/or energy sensor.

Magnetic field sensor comprising two hall elements

Magnetic field sensor and current and/or energy sensor

In an embodiment of the invention, a magnetic sensor comprises an IC magnetic flux sensor and two magnetic flux concentrators (18,19) which are each a section of a ferromagnetic lead frame. A section (18b) of a first magnetic flux concentrator (18), a semiconductor chip (4) and a section (19b) of a second magnetic flux concentrator create a sub-unit (18b;4;19b) having three sandwich like layers (I,II,III). A further section (18a) of first magnetic flux concentrator (18) is a sheet metal object having the shape of a single staircase-like step. The step exhibits a first surface section (22) and a second surface section (23) parallel thereto. One side of first surface section (22) is disposed on top of semiconductor chip (4) in the first layer (I). Second surface section (23) and semiconductor chip (4) are disposed in the second layer (II). A section (17) of a non-ferromagnetic lead frame mounting semiconductor chip (4) and the second magnetic flux concentrator (19) are disposed in the third layer (III). The configuration can without difficulty be assembled and packaged in a conventional assembly line, whereby expensive alignment operations during assembly and the occurrence of relatively large and inaccurate air-gaps can be avoided.

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Zug, Switzerland

Jan Hrejsa