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AS5030

Datasheet - Application In formatio n

8.8 Accuracy of the Encoder System

This chapter describes which individual factors influence the accuracy of the encoder system and how to improve them.

Accuracy is defined as the difference between measured angle and actual angle. This is not to be confused with resolution, which is the smallest

step that the system can resolve.

The two parameters are not necessarily linked together. A high resolution encoder may not necessarily be highly accurate as well.

8.8.1 Quantization Error

There is however a direct link between resolution and accuracy, which is the quantization error:

Figure 28. Quantization Error of a Low Resolution and a High Resolution System

The resolution of the encoder determines the smallest step size. The angle error caused by quantization cannot get better than ± ½ LSB. As

shown in Figure 28, a higher resolution system (right picture) has a smaller quantization error, as the step size is smaller.

For the AS5030, the quantization error is ± ½ LSB = ± 0.7°

Figure 29. Typical INL Error Over 360°

+½ LSB

-½ LSB

ideal function

digitized

function

low

resolution

ideal function

digitized

function

+½ LSB

-½ LSB

error

high

resolution

Quantization

Error

INL including quantization error

-1,5

-1

-0,5

0

0,5

1

1,5

0

45

90

135

180

225

270

315

360

Angle steps

INL

Average (16x)