DRV5056: Any device can measutre the rotation of motor?

Lijia,

Thank you for contacting us with this question.  One particular challenge in this application is that the sensor must be able to detect both a North and South field as the magnet rotates.  Since DRV5056 is a unipolar device, it would not be suitable for 360 degree detection. A single DRV5056 is really only able to determine about 90 degrees.

A better choice for an analog output would be DRV5055A3 which has a linear sensing range up to +/-85 mT.  To support full 360 degree detection, it requires 2 of these 90 degrees mechanically out of phase.  Details regarding this solution method can be found in these documents

https://www.ti.com/lit/pdf/sbaa503

https://www.ti.com/lit/pdf/slyu048

https://www.ti.com/lit/pdf/slya036

The accuracy will largely depend on the mechanical tolerances and sensitivity matching between the two components.  Calibration will very likely be necessary to ensure best performance.

Another alternative approach is to use a 3D linear sensor like TMAG5170-Q1.  This device has 3 axes of sensitivity and selectable input ranges of +/-25 mT, +/-50 mT, and +/-100 mT.  This device utilizes an SPI interface and can generate angle output.  Depending on the alignment selected and the mechanical tolerances, 0.2 degrees can be accomplished using calibration.  However, depending on the rotation speed the conversion latency can become a concern.  More details using this device can be found in these documents

https://www.ti.com/lit/pdf/sbaa463

https://training.ti.com/ti-precision-labs-magnetic-sensors-angle-detection?context=1139747-1139746-1137749-1139635-1148102

Thanks,

Scott