AS5030_1 Datasheet, PDF (26/33 Pages) ams AG – 8 BIT PROGRAMMABLE HIGH SPEED MAGNETIC ROTARY ENCODER

AS5030 8-bit Programmable Magnetic Rotary Encoder
10 Choosing the proper magnet
typ. 6mm diameter
N
R1
Vertical field
component
S
Magnet axis
Magnet axis
NS
Vertical field
component
Bz
R1 concentric circle;
radius 1.0 mm
(20…80mT)
There is no strict requirement on the type or shape of the magnet to
be used with the AS5030. It can be cylindrical as well as square in
shape. The key parameter is that the vertical magnetic field Bz,
measured at a radius of 1mm from the rotation axis is sinusoidal
with a peak amplitude of 20 ~ 80mT (see Figure 31).
10.1 Magnet Placement:
Ideally, the center of the magnet, the diagonal center of the IC and
the rotation axis of the magnet should be in one vertical line.
The lateral displacement of the magnet should be within
±
0.25mm from the IC package center or ± 0.5mm from the IC center,
including the placement of the chip within the IC package.
The vertical distance should be chosen such that the magnetic field
on the die surface is within the specified limits. The typical
distance “z” between the magnet and the package surface is 0.5mm
to 1.8mm with the recommended magnet (6mm x 2.5mm). Larger
gaps are possible, as long as the required magnetic field strength
stays within the defined limits.
A magnetic field outside the specified range may still produce
acceptable results, but with reduced accuracy. The out-of-range
condition will be indicated, when the AGC is at the limits
(AGC= 0 : field too strong;
AGC=63=(3FH): field too weak or missing magnet.
0
360
Figure 31: Vertical magnetic fields of a rotating magnet
360
Bz; 6mm magnet @y=0; z=1mm
N
150
S
100
50
0
-50
-100
Hall elements (side view)
-150
3,5
2,5
1,5
0,5
-0,5
-1,5
-2,5
-3,5
X-displacement [mm]
Figure 32: Bz field distribution along the x-axis of a 6mmØ diametric magnetized magnet
Rev. 1.8
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