Resettable bipolar switch sensor

Abstract

A resettable bipolar switch sensor is disclosed which comprises a bipolar magnetic hysteresis switch sensor, a reset coil, an ASIC switch circuit and a power reset circuit. The bipolar magnetic hysteresis switch sensor comprises a substrate and a magnetoresistive sensing arm located on the substrate. The magnetoresistive sensing arm is of a two-port structure composed of one or more magnetoresistive sensing unit strings arranged in series, parallel, or series-parallel. The magnetization direction of a free layer of a TMR magnetoresistive sensing unit is determined by an anisotropy field Hk, and together with the magnetization direction of a reference layer and the applied magnetic field, it can orient in an N or S direction. The reset coil is located between the substrate along with the magnetoresistive sensing unit, or it is located on a lead frame below the substrate. The direction of the reset magnetic field is either N or S. The ASIC switch circuit comprises a biasing circuit module, a reading circuit module, and an output circuit module. The power reset circuit is connected to the reset coil. This device has the advantages of low power consumption and small size in addition to the capability to set initial state of the switch sensor.