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5
Calibration of TLE4997 Temperature Compensation
A temperature compensation mechanism is implemented in the TLE4997 to account for thermal drift of the Hall
probe sensitivity and thermal reduction of the remanent magnetization of a permanent magnet used in a position
sensing application. Initially, the TLE4997 is pre-configured by Infineon to have a constant magnetic sensitivity
over temperature.
In case the TLE4997 is used to measure an absolute magnetic field, for example in a current sensing application,
then no additional adaption of the temperature compensation by the user is required.
If the TLE4997 is used in a position sensing application where it measures the magnetic field generated by a
moving permanent magnet, then it is typically desired that the output signal of the TLE4997 depend only on the
magnet position. In this case, a user adaptation of the temperature compensation is required to account for thermal
reduction of the magnet's remanence. Therefore, the TLE4997 has to be configured to increase its sensitivity
accordingly with increasing temperature to compensate the thermal reduction of the remanence.
This temperature coefficient of the remanence depends on the chosen magnet material, so the temperature
compensation of the TLE4997 has to be adapted to the permanent magnet employed in the application.
5.1
Integrated Temperature Polynomial
The integrated temperature compensation of the TLE4997 uses a third order polynomial, as shown in
Equation
(5.1).
(
)
S
TCAL
1
=
+
DSP
with:
⋅
TCAL
16
=
T
is the junction temperature in °C. The coefficients TL, TQ, and TT are the linear, quadratic and cubic
J
temperature compensation coefficients, respectively. They are stored in the EEPROM and pre-configured by
Infineon for a constant magnetic sensitivity over temperature (see
The coefficients TL and TQ can be adapted by the user to implement a compensation of the thermal reduction of
a magnet's remanence. The coefficient TT is fixed to the value pre-calibrated by Infineon. It cannot be adapted.
5.2
Application Sensitivity Polynomial
In order to find the optimum TL and TQ parameters to minimized the position signal error due to the thermal
reduction of the magnet's remanence, an application sensitivity polynomial has to be derived from a sensitivity
measurement in the application over temperature that describes the desired sensitivity factor as a function of
temperature (see
Chapter
(
)
S
T
1
TC
=
+
App
J
T
is the junction temperature in °C, TC
J
application temperature coefficients and T
User's Manual
TL 160
TCAL
⎛
⎞
–
--------------------- -
⋅
--------------- -
⎝
⎠
⋅
8 8192
16
(
)
T
48
–
J
5.3). The application sensitivity polynomial is given by
(
)
(
T
T
TC
T
–
+
1
J
0
2
J
(in ppm/°C) and TC
1
(in °C) is a reference temperature.
0
Calibration of TLE4997 Temperature Compensation
TQ 128
TCAL
⎛
–
--------------------------- -
⋅
--------------- -
+
⎝
⋅
1024 8192
16
Chapter 3.5
2
)
T
–
0
(in ppm/°C
2
25
User's Manual
2
TT 64
⎞
–
--------------------------------- -
⋅
+
⎠
⋅
131072 8192
for EEPROM map).
Equation
(5.3).
2
) are the first and second order
v01_01, 2019-08
TLE4997
3
TCAL
⎛
⎞
--------------- -
⎝
⎠
16
(5.1)
(5.2)
(5.3)
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