TLE4997
User’s Manual
Calibration of TLE4997 Temperature Compensation
User’s Manual
28
v01_01, 2019-08
Figure 5-3 Example Polynomial Fit Procedure.
•
Derive the coefficients of the application sensitivity polynomial from the parameters a, b, and c obtained from
the quadratic fit using
.
(5.8)
(5.9)
5.4
Calculation of Final Temperature Compensation Parameters
After determination of the application sensitivity polynomial S
app
, it is necessary to adapt the temperature
compensation paramters TL and TQ in the EEPROM such that the overall sensitivity of the TLE4997 shows the
desired increase over temperature to compensate for the thermal reduction of the magnet’s remanence in the
application.
5.4.1
Algorithm for Finding the Optimum Temperature Coefficient Set
For an optimum temperature compensation in the application, the set of coefficients TL and TQ have to be found
that best fulfill the condition stated in
. To find this parameter set, an error function
ε
(T) is defined
in that is minimized in an iterative procedure.
(5.10)
S
DSPfinal
(T
J
) is the integrated temperature polynomial given by the combination of
, 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
. C is a constant to be varied in the iterative procedure.
y = 2,135E-06x
2
+ 6,550E-04x + 1,305E+00
1,26
1,28
1,30
1,32
1,34
1,36
1,38
1,40
1,42
1,44
-50
0
50
100
150
Sensi
ti
v
it
y
correcti
on
S(T
J
)
T
J
(
°
C)
S(i)
Quadratic fit
a = 1.305, b = 6.55E-4°C
-1
, c = 2.135E-6°C
-2
TC
1
b 2 c T
0
⋅ ⋅
+
a b T
0
c T
0
2
⋅
+
⋅
+
------------------------------------------
=
TC
2
c
a b T
0
c T
0
2
⋅
+
⋅
+
------------------------------------------
=
ε
T
J
( )
S
DSPfinal
T
J
( )
C S
DSPpre
T
J
( )
S
app
T
J
( )
⋅
⋅
---------------------------------------------------------------- 1
–
=
