as5055 austriamicrosystems, as5055 Datasheet - Page 19

• Manufacturer Part Number: as5055
• Description: Low Power 12 Bit Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5055
Data Sheet – Placement of the Magnet
12 Placement of the Magnet
12.1 Non-Linearity Error over Displacement
As shown in Figure 17, the recommended horizontal position of the magnet axis is over the diagonal center of the IC.
Figure 16 shows a typical error curve at a vertical magnet distance of 1.0mm, measured with a NdFeB N35H magnet
with 6mm diameter and 2.5mm height.
The X- and Y- axis of the graph indicate the lateral displacement of the magnet center with respect to the IC center.
At X = Y = 0, the magnet is perfectly centered over the IC. The total displacement plotted on the graph is for ± 1mm in
both directions.
The Z-axis displays the worst case INL error over a full turn at each given X-and Y- displacement. The error includes
the quantization error of ± ½ LSB. At the sample shown in Figure 16, the accuracy for a centered magnet is better than
0.5°. Within a radius of 0.5mm, the accuracy is abo ut 1.0° (spec = 1.41° over temperature).
Figure 16. Integral Non-Linearity over Displacement of the Magnet
www.austriamicrosystems.com
INL [° ]
3,5
4
2,5
3
1,5
0,5
2
1
0
X-displacement [mm]
Revision 1.2
Non-Linearity @ z=1mm
-1,0
-0,7
-0,4
-0,1
0,2
0,5
Y-displacement [mm]
0,8
3,5-4
3-3,5
2,5-3
2-2,5
1,5-2
1-1,5
0,5-1
0-0,5
19 – 22