IC-MA3 Datasheet, PDF (8/19 Pages) IC-Haus GmbH – ANGULAR HALL SENSOR

iC-MA3 ANGULAR HALL SENSOR
WITH SIN/COS OUTPUT, CASCADABLE
HALL SENSORS
Rev A2, Page 8/19
Principle of operation
S
N
z
y
B
+B_z
x
16
15
14
13
1
12
PSIN
PCOS
2
11
3
10
NCOS
NSIN
4
9
5
6
7
8
-B_z
C151107-1
Figure 1: Principle of magnetic field measurement
using Hall sensors
Figure 2: Position of the Hall sensors in the QFN
package (top view)
The diametric magnet is to be placed centrically above
the device package (Figure 3).
iC-MA3 has four Hall sensors which convert the mag-
netic field into measurable Hall voltages. The arrange-
ment of the array has been specifically selected to allow
a very tolerant assembly of iC-MA3 to the magnet axis.
Solely the magnetic field’s z-component is evaluated at
which the field lines pass through two opposing sensors
in opposite directions (Figure 1).
16
15
14
13
1
12
S
2
11
3
10
4
9
Differential signals are generated by the combination of
two Hall sensors each. When the magnet rotates along
its longitudinal axis, sine and cosine output signals are
created which can be evaluated by the subsequent elec-
tronic to derive the angle position of the axis holding
the magnet.
A diametrically magnetized, cylindrical permanent mag-
net made of Neodymium Iron Boron (NdFeB) or Samar-
ium Cobalt (SmCo) generates optimum sensor signals.
The magnet cylinder’s diameter should be in the range
of 3 mm to 6 mm.
Hall sensor array and zero angle
The four Hall sensors are placed in the center of the
QFN16 package on a circle of 2.1 mm in diameter and
have a 90 ° angle distance to one another (Figure 2).
5
6
7
8
Figure 3: Magnet in zero position (0°)
Each Hall sensor only measures the z-component of
the magnetic field. For the two Hall sensors located
directly beneath the poles, the absolute value of the
measured field strength is maximum but with different
polarity.
For the two Hall sensors which are located at the inter-
face of the north and south pole, the magnetic field has
no component in z-direction, thus, their signal is 0.
When the magnet rotates counterclockwise, the mea-
sured signal changes sinusoidal with the rotary angle.
The angle of 90° between two neighboring Hall sen-
sors yields phase-shifted sine- and cosine-signals with
positive (PSIN, PCOS) and negative (NSIN, NCOS)
polarity.