am256l RLS, am256l Datasheet - Page 11

• Manufacturer Part Number: am256l
• Description: Angular Magnetic Encoder Ic
• Manufacturer: RLS

Data sheet
AM256LD01_03
Issue 3, 14
Recommended magnet
The AM256L can be supplied with a pre-selected magnet to ensure that optimum performance is achieved.
Alternatively, magnets can be sourced from other suppliers but they must conform to the following guidelines
to ensure that performance specifications can be achieved.
To select a suitable magnet it is important to know the properties of the sensors. Hall sensors are only
sensitive to the perpendicular component of the magnetic flux density (B). The AM256L has a Hall sensor
array arranged in a circle with a radius of 1.5 mm. Sensors are located on the surface of the silicon.
Magnets must be cylindrical in shape and diametrically polarized. The main criterion for magnet selection is
the modulation of the perpendicular component of magnetic flux density at the location of the sensors (B
* Typical value of B
** Offset affects the integral nonlinearity if the magnet is not aligned correctly with respect to the chip.
We recommend that a magnet with the following parameters is used to provide the necessary modulation:
* Rare earth material magnets SmCo are recommended; however, NdFeB magnets can be used but they have
© 2009 RLS d.o.o.
Parameter
Amplitude of B
Offset of B
Parameter
Diameter
Length
Material
Material remanence
Temperature coefficient
Curie temperature
different characteristics
proportional to the B
th
n
January 2009
modulation
n
modulation
Fig. 14: Distribution of B
nAmpl
nAmpl
will give an analogue signal output with an amplitude of 0.7 V. The amplitude of the signal is
.
. 1 Tesla equals 10,000 Gauss.
Typ.
4
4
Sm2Co17
10.5
-0.03
720
Fig. 13: Distribution of the perpendicular component of B
Symbol
B
B
nAmpl
nOffset
n
Unit
mm
mm
kGauss
% / °C
°C
and its modulation if the magnet is rotated through 360°
Min.
0
Typ.
605
Note
*
A
Max.
±30
Unit
Gauss
Gauss
Note
*
**
associate company
n
).
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