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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 25. Typical Curves for Vertical Distance versus ACG Value on Several Untrimmed Samples

As shown in Figure 25, the AGC value (left Y-axis) increases with vertical distance of the magnet. Consequently, it is a

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 Figure 25 (right Y-axis) shows that the accuracy of the AS5130

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

rotation axis is sinusoidal with a peak amplitude of 20..80mT (see Figure 26).

Linearity and AGC vs Airgap

0

8

16

24

32

40

48

56

64

0

500

1000

1500

2000

2500

Airgap [µm]

1,0

1,2

1,4

1,6

1,8

2,0

2,2

sample#1

sample#2

sample#3

sample#4

Linearity [°]