AS5045 datasheet(20/24 Pages) AMSCO

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AS5045 12-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER

Revision 1.5

www.austriamicrosystems.com

Page 20 of 24

each pin must be connected to the positive supply at pin

16 (VDD5V).

By hardware: PWM output: The PWM output is a

constant stream of pulses with 1kHz repetition frequency.

In case of power loss, these pulses are missing

14 Angular Output Tolerances

14.1

Accuracy

Accuracy is defined as the error between measured

angle and actual angle. It is influenced by several

factors:

the non-linearity of the analog-digital converters,

internal gain and mismatch errors,

non-linearity due to misalignment of the magnet

As a sum of all these errors, the accuracy with centered

magnet = (Errmax – Errmin)/2 is specified as better than

±0.5 degrees @ 25°C (see Figure 22).

Misalignment of the magnet further reduces the

accuracy. Figure 21 shows an example of a 3D-graph

displaying non-linearity over XY-misalignment. The

center of the square XY-area corresponds to a centered

magnet (see dot in the center of the graph). The X- and

Y- axis extends to a misalignment of

±1mm in both

directions. The total misalignment area of the graph

covers a square of 2x2 mm (79x79mil) with a step size of

100µm.

For each misalignment step, the measurement as shown

in Figure 22 is repeated and the accuracy

(Errmax – Errmin)/2 (e.g. 0.25° in Figure 22) is entered as

the Z-axis in the 3D-graph.

Figure 21: Example of linearity error over XY misalignment

The maximum non-linearity error on this example is

better than

±1 degree (inner circle) over a misalignment

radius of ~0.7mm. For volume production, the placement

tolerance of the IC within the package (

±0.235mm) must

also be taken into account.

The total nonlinearity error over process tolerances,

temperature and a misalignment circle radius of 0.25mm

is specified better than

±1.4 degrees.

The magnet used for this measurement was a cylindrical

NdFeB (Bomatec® BMN-35H) magnet with 6mm diameter

and 2.5mm in height.

Figure 22: Example of linearity error over 360°

-1000

-800

-600

-400

-200

200

400

600

800

1000

Linearity Error over XY-misalignment [°]

Linearity e rro r with centered magnet [degree s]

-0.5

-0.4

-0.3

-0.2

-0.1

0.1

0.2

0.3

0.4

0.5

109

163

217

271

325

379

433

487

541

595

649

703

757

811

865

919

973

transition noise

Errmax

Errmin

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