AS5030ATST datasheet(26/33 Pages) AMSCO

26 / 33 page

AS5030 8-bit Programmable Magnetic Rotary Encoder

Rev. 1.8

www.austriamicrosystems.com

Page 26 of 33

10 Choosing the proper magnet

There is no strict requirement on the type or shape of the magnet to

be used with the AS5030. It can be cylindrical as well as square in

shape. The key parameter is that the vertical magnetic field Bz,

measured at a radius of 1mm from the rotation axis is sinusoidal

with a peak amplitude of 20 ~ 80mT (see Figure 31).

10.1 Magnet Placement:

Ideally, the center of the magnet, the diagonal center of the IC and

the rotation axis of the magnet should be in one vertical line.

The lateral displacement of the magnet should be within

0.25mm from the IC package center or ± 0.5mm from the IC center,

including the placement of the chip within the IC package.

The vertical distance should be chosen such that the magnetic field

on the die surface is within the specified limits. The typical

distance “z” between the magnet and the package surface is 0.5mm

to 1.8mm with the recommended magnet (6mm x 2.5mm). 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

acceptable results, but with reduced accuracy. The out-of-range

condition will be indicated, when the AGC is at the limits

(AGC= 0 : field too strong;

AGC=63=(3FH): field too weak or missing magnet.

Figure 31: Vertical magnetic fields of a rotating magnet

Figure 32: Bz field distribution along the x-axis of a 6mmØ diametric magnetized magnet

Bz; 6mm magnet @y=0; z=1mm

-150

-100

-50

100

150

-3,5

-2,5

-1,5

-0,5

0,5

1,5

2,5

3,5

X-displacement [mm]

Hall elements (side view)

Magnet axis

Vertical field

component

(20…80mT)

360

Vertical field

component

R1 concentric circle;

radius 1.0 mm

Magnet axis

typ. 6mm diameter

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