[FAQ] TMAG5233: Is there an xMR switch replacement using Hall-effect Sensors?

Tool/software:

xMR is a term which generally describes any form of magneto resistive sensor. This includes anisotropic magnetoresistance (AMR), giant magneto resistance (GMR), and tunneling magneto resistance (TMR).  Each of these operates under somewhat different mechanisms, but all of these use structures that will vary in resistivity as the angle of the sensed magnetic field changes.

Particularly in the case of GMR and TMR structures, these are built with complex layering of magnetic and non-magnetic materials that are highly specialized.  They also include a region which has been magnetized during production that is often referred to as a pinned layer.  The magnetization of the pinned layer results with a maximum input magnetic field that if exceeded will re-magnetize this layer and permanently affect the accuracy of the sensor.  The complex layer count and this magnetization result in a higher cost manufacturing flow.

The very high magnetic sensitivity and high resistivity of TMR structures tends to allow for low switching thresholds and low operating currents which are both preferred in switching applications.  Due to their construction, xMR sensors are often sensitive to a magnetic field component in either the X or Y axis directions. 

The high device cost of these sensor materials can make them less desirable in cost sensitive designs. As an alternative, Hall-effect sensors cost advantage make them a practical option when configured correctly.  While these devices have higher current while being sampled, it is possible to reduce the sample rate and have the device in a very low power state when idle.  Many sensing solutions detect interactions with human-machine interface (HMI) controls, and do not require fast sample rates.  Particularly in these cases, Hall-effect sensors like TMAG5233, TMAG5133, and TMAG5134 provide excellent options to consider against an xMR sensor.