AS5130ATST AMSCO [austriamicrosystems AG], AS5130ATST Datasheet - Page 32

• Manufacturer Part Number: AS5130ATST
• Description: 8 Bit Programmable Magnetic Rotary Encoder with Motion Detection & Multiturn
• Manufacturer: AMSCO [austriamicrosystems AG]

AS5130
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Vertical Distance of the Magnet
The chip-internal automatic gain control (AGC) regulates the input signal amplitude for the tracking-ADC to a constant
value. This improves the accuracy of the encoder and enhances the tolerance for the vertical distance of the magnet.
Figure 28. Typical Curves for Vertical Distance versus ACG Value on Several Untrimmed Samples
As shown in
good indicator for determining the vertical position of the magnet, for example as a pushbutton feature, as an indicator
for a defective magnet or as a preventive warning (e.g. for wear on a ball bearing etc.) when the nominal AGC value
drifts away. If the magnet is too close or the magnetic field is too strong, the AGC will be reading 0. If the magnet is too
far away (or missing) or if the magnetic field is too weak, the AGC will be reading 63 (3FH).
The AS5130 will still operate outside the AGC range, but the accuracy may be reduced as the signal amplitude can no
longer be kept at a constant level. The linearity curve in
is best within the AGC range, even slightly better at small airgaps (0.4 – 0.8mm). At very short distances (0 – 0.1) the
accuracy is reduced, mainly due to nonlinearities in the magnetic field. At larger distances, outside the AGC range
(~2.0 – 2.5mm and more) the accuracy is still very good, only slightly decreased from the nominal accuracy. Since the
field strength of a magnet changes with temperature, the AGC will also change when the temperature of the magnet
changes. At low temperatures, the magnetic field will be stronger and the AGC value will decrease. At elevated
temperatures, the magnetic field will be weaker and the AGC value will increase.
Choosing the Proper Magnet
There is no strict requirement on the type or shape of the magnet to be used with the AS5130. It can be cylindrical as
well as square in shape. The key parameter is that the vertical magnetic field B
rotation axis is sinusoidal with a peak amplitude of 20..80mT
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64
56
48
40
32
24
16
8
0
Figure
0
28, the AGC value (left Y-axis) increases with vertical distance of the magnet. Consequently, it is a
sample#1
500
sample#2
Linearity and AGC vs Airgap
1000
Airgap [mm]
Revision 1.00
Figure 28
sample#3
(see Figure
1500
(right Y-axis) shows that the accuracy of the AS5130
29).
sample#4
z
measured at a radius of 1mm from the
2000
Linearity [°]
2500
2,2
2,0
1,8
1,6
1,4
1,2
1,0
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