The magnetic field produced by current confined to a wire or busbar is expressed as circular field lines around the wire. A Crocus TMR sensor has an axis of sensitivity tangential to circular field lines, which is optimal for current sensing. Typical Hall sensor axis of sensitivity is planar or normal to the surface of the IC, which is non-optimal for sensing the circular field from a current trace. Sensor axis of sensitivity and trace routing are very important considerations for system level crosstalk.
Current in adjacent traces will produce circular fields, so current routed by traces in proximity and parallel to the current being sensed will produce unwanted field sensed as cross talk. For a given layout, the Crocus TMR axis of sensitivity parallel to the PCB will reduce crosstalk by an order of magnitude relative to Hall based sensors. In application, the lower crosstalk from Crocus TMR axis of sensitivity enables more accurate measurements and allows a higher density of current traces on a PCB. As shown below a Crocus TMR sensor is impacted by 2% from a stray magnetic field 10mm away while a Hall sensor is impacted by 50%. The result is a low noise, high sensitivity Crocus TMR current sensor, enabling more accurate, stable measurements, resulting in superior performance.