Infineon TLE4997, User Manual

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TLE4997
User’s Manual
Calibration of TLE4997 Temperature Compensation
User’s Manual 26 v01_01, 2019-08
Figure 5-1 Example thermal behavior of magnetic remanence M(T) and application sensitivity polynomial
S
app
(T) with reference temperature 48°C.
The reference temperature T
0
is a degree of freedom that can be chosen by the user, such that the gain of the
TLE4997 that is configured in the EEPROM, applies at this reference temperature.
In case the calibration of the offset and gain for the output charateristic is done after the calibration of the
temperature compensation, the choice of T
0
is not relevant. In this case, the gain at a specific temperature is
configured separately. A choice of T
0
= 48°C is recommended for simplicity (to match the reference temperature
in the definition of TCAL in Equation (5.2) ).
The application sensitivity polynomial S
App
has to be determined in the application to approximately cancel the
temperature dependency of the remanence, as stated in Equation (5.4) and illustrated in Figure 5-1 .
(5.4)
M
R
is the remanence of the permanent magnet as a function of temperature and T
A
is the ambient temperature in
the application that relates to the junction temperature T
J
by Equation (5.5) .
(5.5)
R
th
is the thermal resistance of the TLE4997 as specified in the data sheet, U is the supply voltage and I is the
supply current.
After determining the application sensitivity polynomial S
App
from a sensitivity measurement over temperature, the
sensor parameters TL
final
and TQ
final
for the final sensor configuration have to be adapted to combine the
compensation of the Hall sensing element drift (given by the precalibrated values TL
pre
and TQ
pre
) and the
cancellation of the thermal reduction of the magnet’s remanence (given by S
App
), as stated in Equation (5.6) .
(5.6)
S
DSPfinal
(T
J
) is the integrated temperature polynomial given by the combination of Equation (5.1) and
Equation (5.2) , with the final parameters TL
final
and TQ
final
. S
DSPpre
(T
J
) is the integrated temperature polynomial
with the pre-configured parameters TL
pre
and TQ
pre
.
After determination of the application sensitivity polynomial coefficients and readout of the pre-configured TL
pre
,
TQ
pre
, and TT parameters via the programming interface, the optimum TL
final
and TQ
final
parameters have to be
derived from Equation (5.6) and programmed into the TLE4997.
0,925
0,950
0,975
1,000
1,025
1,050
1,075
-50 0 50 100 150
Rel.
C
hange
T
J
(
°
C)
MR(T)
Sapp(T)
MR(T)*Sapp(T)
S
App
T
J
( )
M
R
T
A
( )
cons t tan
≈ ⋅
T
J
T
A
R
th
U I
⋅ ( ) ⋅
+ =
S
DSPfinal
T
J
( )
S
DSPpre
T
J
( )
S
App
T
J
( ) ⋅ ≈