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AS5130

Datasheet - Application In form atio n

Figure 31. Typical Error Curve of INL Error Over Lateral Displacement (including quantization error)

8.4.6 Magnet Size

Figure 29 to Figure 31 illustrate a cylindrical magnet with a diameter of 6mm. Smaller magnets may also be used, but since the poles are closer

together, the linear range will also be smaller and consequently the tolerance for lateral misalignment will also be smaller.

If the ±0.25mm lateral misalignment radius (rotation axis to IC package center) is too tight, a larger magnet can be used. Larger magnets have a

larger linear range and allow more misalignment. However at the same time the slope of the magnet is more flat, which results in a lower

differential amplitude. This requires either a stronger magnet or a smaller gap between IC and magnet in order to operate in the amplitude-

controlled area (AGC > 0 and AGC < 63).

In any case, if a magnet other than the recommended 6mm diameter magnet is used, two parameters should be verified:

Verify, that the magnetic field produces a sinusoidal wave, when the magnet is rotated. Note that this can be done with the SIN-/COS- out-

puts of the AS5130; e.g. rotate the magnet at constant speed and analyze the SIN- (or COS-) output with an FFT-analyzer. It is recom-

mended to disable the AGC for this test (see Analog Sin/Cos Outputs with External Interpolator on page 13).

Figure 29 or Figure 30). Furthermore, the sinewave tests described above may be re-run at defined X-and Y- misplacements of the magnet

to determine the maximum acceptable lateral displacement range. It is recommended to disable the AGC for both these tests (see Analog

Sin/Cos Outputs with External Interpolator on page 13).

Note:

For preferred magnet suppliers, please refer to the austriamicrosystems website (Rotary Encoder section).

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INL [°]

X Displacement [µm]

Y Displacement [µm]

INL vs. Displacement: AS5030 for AGC24

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