User’s Manual 16 Rev. 1.0
2019-04-29
TLE5501
TMR-Based Angle Sensor
Calibration
Therefore, the following relation has to be ensured by the user over the complete lifetime:
B
min
= 0.9B
0
< B < 1.1B
0
= B
max
; with B
0
: magnetic field at 25°C/0h and B
min
, B
max
: minimum and maximum
magnetic field at initial calibration condition (25°C) over lifetime
The temperature behavior of B
min
and B
max
is given by the temperature coefficient of the magnet material.
An example for an initial calibration point at 25°C/50mT/0h is shown in Figure 15.
Figure 15 One-time calibration a 25°C/50mT. Dashed lines show the allowed magnetic field range
taking into account the temperature effect and aging of the magnet. Assumptions: ferrite
magnet material with TC = -2000ppm/K, 10% field strength variation from initial calibration
condition (25°C/50mT) over lifetime.
Figure 16 shows the typical angle error for a sensor which has its initial calibration of offset, amplitude and
orthogonality error at 25°C/50mT. Due to aging effects of the magnet, it is assumed that the magnetic field at
25°C is reduced by 10% to 45mT. The sensor is still operated with calibration parameters coming from initial
calibration at 25°C/50mT, thus having no longer optimized calibration values. Over temperature, the magnetic
field is changing with a T
C
of -2000pm/K (ferrite magnet material is assumed). This means that the magnetic
field at the sensor deviates more or less (depending on temperature) from the initial calibration condition B
0
= 50mT. This deviation causes an angle error which is shown in Figure 16.
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
-50 -25 0 25 50 75 100 125 150
B (mT)
T (°C)
B_tol,max
B_tol,min
Calibration @25°C
Bmin
Bmax
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