AMSCO AS5304

AS5304
Magnet Specification
Magnetic Multipole Ring, MR20-44
Pole Length 2.0 mm, 44 Poles
1
General Description
This specification defines the dimensional and magnetic properties of a multipole magnetic ring for
use with the AS5304 magnetic encoder for off-axis rotary applications.
Figure 1
AS5304 with multipole ring magnet for off-axis rotary motion sensing (not to scale)
Note:
The MR20-44 magnet contains only the magnetic ring (see picture on the right), the metal carrier is
shown for illustration purposes only
2
Multipole Ring Magnets for the AS5304
Figure 2 shows the proper placement of a multipole ring over the AS5304. The centerline of the
magnetic ring (median Hall sensor scan path) is located over the Hall array (see Figure 3).
The magnetic ring is designed such that the pole length lp matches the required length at the scan
path (typically the center) of the ring. The IC is oriented in perpendicular with respect to the rotation
center.
The correct measurement radius can be calculated by the number of poles of the magnet ring and
the specified pole length:
These figures can be determined by the code of the magnet:
AS5304 Magnet Specification
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MR20-44
Number of poles
M: Magnet
Nominal pole length in 1/10 mm
AS5304 = 20 (2.0mm)
AS5306 = 12 (1.2mm)
R: Ring
S: Strip
The correct measurement radius for the MR20-44 magnet ring is therefore:
rm =
pole _ length(mm) * number _ of _ poles
2 *π
rm =
2.0 * 44
= 14.00mm
2 *π
Figure 2
Proper placement of the ring magnet (not to scale)
lp
ro r
i
rm
median Hall sensor
scan path
AS5304 Magnet Specification
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3
Locating the Hall Sensor Array
The measurement radius should coincide with the Hall sensor array on the chip. The location of the
Hall sensors can be seen in Figure 3. The Hall sensor array is located 1.02mm above the horizontal
centerline of the TSSOP-20 package, or
3.20mm + 1.02mm = 4.22mm above the edge of pins #1….10 (top view, pin#1 at bottom left).
Figure 3
Location of Hall sensors in the TSSOP-20 package
0.2299±0.100
1.02
Die C/L
3.200±0.235
0.2341±0.100
Package
Outline
0.7701±0.150
3.0475±0.235
4
Dimensional Specification
Magnet Order # AS5000-MR20-44 on ams web shop www.ams.com/ICdirect
Parameter
Sym
bol
Min
Typ
Max
Unit
Magnet material
Plastic bonded Strontium Ferrite
SrFe. Supplier-internal material
grade = BMNP-1612.
Remanence
Br
Pole length
lp
280
300
2.0
Number of poles
Inner ring radius
Note
mT
mm
Suited for AS5304
44
ri
11.975
Resolution
12
12.025
3520
Res
Measurement
radius
rm
Outer ring radius
ro
AS5304 Magnet Specification
15.975
mm
step
s/rev
11.78
bit
880
ppr
14.00
mm
16
16.025
2013-Sep [1-00]
With AS5304 @ 160x
interpolation
Pole length* number of poles / 2π
mm
page 4/7
Strip thickness
d
1.5
1.5
1.6
mm
Magnetic
amplitude
Amag
52
76
89
mT
25
mT
Amplitude
variation
Temperature
range
Tamb
Tbd
°C
Magnetic
temperature drift
Tdmag
Tbd
%/K
5
Mechanical Drawing
6
Marking
Measured at magnet surface
The magnet ring has two marks at the backside:
One mark shows the number of poles (44) the other mark shows a single digit letter (A…F), which is
of no relevance.
AS5304 Magnet Specification
2013-Sep [1-00]
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Figure 4
Markings at the backside of the magnet
7
Mounting the Magnet Ring
As mentioned in chapter 5, the magnet ring has two markings, which represent the backside of the
ring. The front side should be facing the AS5304 IC with a gap of <lp/2 = <1.0mm.
The magnet ring may be mounted directly on magnetic or non-magnetic surfaces. When magnetic
surfaces are used, the ring may 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.
Depending on the carrier material, there are several adhesives available to glue the ring to the
surface. For general ruggedness and vibration demands, the use of two-component-adhesive
(binder + hardener) has proven to be successful in most cases.
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 ams website.
8
Magnet Supplier Information
Bomatec AG
Hofstrasse 1
CH-8181 Höri
Tel. +41 44 872 10 00
www.bomatec.ch
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2013-Sep [1-00]
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Copyrights
Copyright ams AG, Tobelbader Strasse 30, 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.
Disclaimer
Devices sold by ams AG are covered by the warranty and patent indemnification provisions
appearing in its Term of Sale. ams AG makes no warranty, express, statutory, implied, or by
description regarding the information set forth herein. ams 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 ams AG for current information. This product is intended
for use in commercial applications. Applications requiring extended temperature range, unusual
environmental requirements, or high reliability applications, such as military, medical life-support or
life-sustaining equipment are specifically not recommended without additional processing by ams
AG for each application. This Product is provided by ams “AS IS” and any express or implied
warranties, including, but not limited to the implied warranties of merchantability and fitness for a
particular purpose are disclaimed.
ams 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,
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furnishing, performance or use of the technical data herein. No obligation or liability to recipient or
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Contact Information
Headquarters
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten
Austria, Europe
Tel: +43 (0) 3136 500 0
Website: www.ams.com
For Sales Offices, Distributors and Representatives, please visit:
www.ams.com/contact
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