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AS5215

Datasheet - Detailed Descr i pti on

7.1.2 Magnet Thickness

Figure 6 shows the relationship of the peak amplitude in a rotating system (essentially the magnetic field strength of the Bz field component) in

relation to the thickness of the magnet. The X-axis shows the ratio of magnet thickness (or height) [h] to magnet diameter [d] and the Y-axis

shows the relative peak amplitude with reference to the recommended magnet (d=6mm, h=2.5mm). This results in an h/d ratio of 0.42.

Figure 6. Relationship of Peak Amplitude vs. Magnet Thickness

As the graph in Figure 6 shows, the amplitude drops significantly at h/d ratios below this value and remains relatively flat at ratios above 1.3.

Therefore, the recommended thickness of 2.5mm (at 6mm diameter) should be considered as the low limit with regards to magnet thickness.

It is possible to get 40% or more signal amplitude by using thicker magnets. However, the gain in signal amplitude becomes less significant for h/

d ratios >~1.3. Therefore, the recommended magnet thickness for a 6mm diameter magnet is between 2.5 and ~8 mm.

Bz amplitude vs. magnet thickness

of a cylindrical diametric magnet with 6mm diameter

0%

20%

40%

60%

80%

100%

120%

140%

160%

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

thickness to diameter [h/d] ratio

d= 6mm x h= 2.5mm ref. magnet:

h/d = 0.42

Rel. amplitude = 100%