Datasheet

AS5306
Magnet Specification
Magnetic Multipole Strip MS12-250
Pole Length 1.2mm, 250 Poles
1 General
This specification defines the dimensional and magnetic properties of a multipole magnetic strip for use with the
AS5306 magnetic linear motion and off-axis rotary angle encoder.
Material: Strontium ferrite bonded
2 Dimensional Specification
Parameter
Symbol
Min
Typ
Max
Unit
Note
Strip Length
L
300±2
mm
Active length = 300
Strip Width
W
10±0.2
mm
Active width = 10mm
Strip Thickness
T
1.3±0.
15
mm
1mm rubber bonded magnet on
0.3mm stainless steel strip
Thermal Expansion
Density
Delivery
-6
17
x10 /K Mechanical length expansion
3.5
3.65
3.8
1.43
4.64
7.85
g/cm
3
magnetic rubber
stainless steel
Single cut pieces without adhesive, rolls of 25m, 50m (up to 100m max.)
3 Magnet Specification
Parameter
Pole Length
Symbol
Lp
Pole Length Deviation
Min
Typ
1.20
1
Amplitude Variation
Number of Poles
Resolution
Res
Magnetic Field Amplitude
@ 0.4mm Distance
Bpk
Magnetic Field Temperature
Drift
TkBr
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Max
Unit
mm
1.5
% of
2*Lp
±10
% of Bpk
Note
Results in pole pair length of 2,40mm
(250 poles @ 1.2mm)
Measured at Bz=0,
active area
all poles within
All poles within active area
Excluding poles with L<L P at the ends
of the strip
250
poles
15
µm
AS5306 @ incremental output
mT
Vertical component of the magnetic
field strength in the center of the strip
at 25°C
-0.2
Revision 0.1
%/K
1-6
AS53xx Linear Multipole Magnetic Strip
Magnet Specification
Parameter
Symbol
Min
Typ
Max
Unit
Note
depending on accuracy grade
40
Cumulative error
20
standard
µm/m
10
A20
A10
Thermal Expansion
Temperature Range
Tamb
-40
25
1E-4
1/K
Mechanical length expansion
100
°C
scale mounted, no bending
Magnetization
The MS12-250 magnet strip is magnetized on the top side and bonded on a steel support with elastomer adhesive
(bottom). Note that the polarization of the magnet will change when it is rotated as the pole arrangement not
symmetric. This will influence the position of the index pulse.
An index pulse is generated when the North and South poles are placed over the Hall array as shown in Figure 2.
The incremental output count increases when the magnet is moving to the left, facing the chip with pin#1 at the
lower left corner (see Figure 2, top drawing). At the same time, the absolute position information increases.
Likewise, the position information decreases when the magnet is moved in the opposite direction. Note that there is
no hysteresis at the absolute output. In order to get a stable 12-bit absolute reading, it may be necessary to filter
the values by averaging, e.g. a moving average calculation in the external microcontroller. Averaging 4 readings
results in 6dB (=50%) noise and jitter reduction. An average of 16 readings reduces the jitter by a factor of 4.
Mounting the Magnet Strip
The magnet strip may be mounted directly on magnetic or non-magnetic surfaces. When magnetic surfaces are
used, the strip must be mounted on top of the surface, but not immersed in a cavity, as this may weaken the
magnetic field of the magnet. When mounting the magnet on a non-magnetic surface, either method is acceptable.
For more rigid demands, magnet suppliers offer customized solutions where the magnet material is directly
overmolded on the carrier, e.g. a shaft, bushing, plate, etc..
Please contact your magnet supplier for more information. A list of recommended suppliers is available for
download on the austriamicrosystems website.
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Revision 0.1
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4 Magnet Dimensions
MS12-250 strip dimensions
10
W = 10
Bpk Bpk
Figure 1:
1
2
3
4
5
6
7
8
247
248
249
250
N
S
N
S
N
S
N
S
N
S
N
S
recommended
scanning path
T = 1.2
L =2.4
L = 300
Alignment of Magnet Strip and Sensor IC
When aligning the magnet strip to the AS5306 sensor IC, the centerline of the magnet strip should be placed
exactly over the Hall array. See Figure 2 for the position of the Hall array relative to Pin #1.
Vertical Distance
The vertical distance between the magnet strip and the top of the IC package should be ≤ 0.4mm. Note that the
vertical distance depends on the strength of the magnet. The AS5306 automatically adjusts for fluctuating magnet
strength by using an automatic gain control (AGC). There are several indicators for proper magnetic field strength
available with the AS5306. The vertical distance should be set such that the AO voltage is between 1.0 and 4.0V.
See the AS5306 datasheet for more details.
See also Error! Reference source not found. for measurement data of the MS12-250 magnetic strip.
Lateral Stroke
The lateral movement range (stroke) can cover the active area of the magnetic strip (see Figure 1) as long as all
Hall sensors of the IC are covered by the magnet. The Hall array on the AS5306 has a length of 2.0mm, hence the
total stroke is
Stroke = Length of active area – length of Hal array = 300.0mm – 2.0mm = 298.0mm
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AS53xx Linear Multipole Magnetic Strip
Magnet Specification
Figure 2:
Alignment of magnet strip with AS5306 sensor IC
position value
increases
leftmost magnet position
Die C/L
S
N
S
N
S
N
S
N
S
3.0475±0.235
N
AS5306
Package
Outline
1.00
position value
decreases
rightmost magnet position
S
2.576±0.235
3.200±0.235
Die C/L
N
S
N
S
N
S
N
S
N
1.00
3.0475±0.235
vertical airgap
magnet
strip
carrier
see text
1.00 ± 0.1
Note: all dimensions are in mm
Note that the polarization of the magnet will be reversed when it is rotated or flipped (see Magnetization for more
details).
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Revision 0.1
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AS53xx Linear Multipole Magnetic Strip
Magnet Specification
5 Adhesive Tape Specification
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Revision 0.1
5-6
Copyrights
Copyright © 2011, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe.
Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged,
translated, stored, or used without the prior written consent of the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions
appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by
description regarding the information set forth herein or regarding the freedom of the described devices from patent
infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and
without notice. Therefore, prior to designing this product into a system, it is necessary to check with
austriamicrosystems AG for current information. This product is intended for use in normal commercial
applications. Applications requiring extended temperature range, unusual environmental requirements, or high
reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not
recommended without additional processing by austriamicrosystems AG for each application.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited
to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special,
incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or
use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of
austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters
austriamicrosystems AG
A-8141 Schloss Premstaetten, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
Magnet Supplier Information
Bogen Electronic GmbH1,
Potsdamer Strasse 12-13
14163 Berlin
Germany
http://www.bogen-electronic.de/
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
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