AS5035 – 64 PPR INCREMENTAL MAGNETIC ROTARY ENCODER

Revision 1.5

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The magnet’s field strength perpendicular to the die

surface should be verified using a gauss-meter. The

circle with a radius of 1.1mm (R1), should be in the range

of ±45mT…±75mT. (see Figure 10).

9.1

Physical Placement of the Magnet

The best linearity can be achieved by placing the center

of the magnet exactly over the defined center of the IC

package as shown in Figure 11:

1

Defined

center

2.433 mm

2.433 mm

3.9 mm

3.9 mm

Area of recommended maximum

magnet misalignment

Figure 11: Defined IC center and magnet displacement radius

Magnet Placement:

The magnet’s center axis should be aligned within a

center of the IC with reference to the edge of pin #1 (see

Figure 11). This radius includes the placement tolerance

of the chip within the SSOP-16 package (+/- 0.235mm).

the center of the chip

The vertical distance should be chosen such that the

magnetic field on the die surface is within the specified

limits (see Figure 10). The typical distance “z” between

the magnet and the package surface is 0.5mm to 1.8mm

with the recommended magnet (6mm x 3mm). Larger

gaps are possible, as long as the required magnetic field

strength stays within the defined limits.

A magnetic field outside the specified range may still

produce usable results, but the out-of-range condition

will be indicated by MagINCn (pin 1) and MagDECn (pin

2), see 5.5.

1.282mm ± 0.15mm

0.576mm ± 0.1mm

z

S

N

Package surface

Die surface

Figure 12: Vertical placement of the magnet

10 Angular Output Tolerances

10.1 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

±0.5 degrees @ 25°C (see Figure 14).

Misalignment of the magnet further reduces the

accuracy. Figure 14 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.

Figure 13: Example of linearity error over XY misalignment

-1000

-700

-400

-100

200

500

800

0

1

2

3

4

5

6

°

x

y