Magnet Selection Guideline for Shaft-End configuration

The AKM rotation angle sensor (AK7455) enables the measurement of magnetic fields (Bx, By) parallel to the chip surface and can detect the absolute angle of the magnetic field over the full range of 0 to 360 degrees.

A non-contact rotation angle sensor can be easily built with only a magnet and a sensor. However, for those who have never used a magnetic-based sensor until now or are considering AKM's rotation angle sensor for the first time, it is not easy to select the optimal magnet and determine the sensor arrangement. This document is a guideline for magnet selection when constructing a magnetic encoder system in the Shaft-End Configuration.

The Shaft-End Configuration is where the magnet center and sensor center are aligned on the axis of rotation as shown in Figure 1. Figure 2 shows the magnetic fields (Bx, By) with respect to the rotation angle for the Shaft-End Configuration.