tle4998 Infineon Technologies Corporation, tle4998 Datasheet - Page 10

• Manufacturer Part Number: tle4998
• Description: Programmable Linear Hall Sensor
• Manufacturer: Infineon Technologies Corporation

equipment is required, but as it is a low cost device (for a first evaluation only) it does not (and can not) unveil the
full performance of the TLE4998.
3.2
With the given measurement setup it is possible to acquire the application sensitivity behaviour by measuring the
sensor output
keeping the other parameters constant. We also have to take into account the zero field output of the sensor
this sensitivity to be exactly unity (it will be done in the next step):
Considering
We can then generate a quadratic polynomial fit using the least squares error method or other approaches (Please
check any standard math textbook for this task). An easy way is using Microsoft
polynomial fit. Excel can also display the function of the second order fit in the form
comparing this to
easiest set of user coefficients is found by choosing
by taking
The exact normalization is not very important because it will be corrected by the gain factor G factor during the
subsequent two-point calibration.
series of output values.
3.2.1
In the special case if the user reference temperature is not chosen as 0°C, the conversion from the Excel values
is slightly less straightforward. The mapping between the user coefficients
parameters a, b and c can be obtained using the following formulas:
Temperature Coefficient Setup Guide
User’s Manual
OUT
S
S
S
TC1
TC2
app unnorm
user unnorm
user unnorm
user
user
,
0
,
,
and divide by it to cancel out the units. The subscript unnorm points out that we don’t yet want to normalize
=
=
TC1
------------------------------------------------------------------ -
a
------------------------------------------------------------------ -
a
Equation
Finding the User Coefficients to Compensate the Magnetic Circuit Behaviour
Special Case of Non-Zero TR
(
(
(
+
+
T
user
OUT
T
T
k
b T0
b T0
k
k
)
)
)
⋅
⋅
b
Equation (6)
=
, generate an XY-graph out of this dataset and use the trendline function to get a 2
=
=
+
B
OUT
------------------------------------------------- -
T ( )
2c T0
user
user
------------------------------------------------- -
OUT
b a ⁄
(7), the user polynomial
c
⋅
+
+
for a point with non-zero magnetic field at at least three different temperatures
B
B
°C
c T0
c T0
(
OUT
user
OUT
(
T
⋅
⋅
T
-1
k
k
) OUT
(
and
) OUT
–
S
0
user
user
–
0
user
Figure 2
TC2
2
2
T ( )
0
0
user
=
gives an example how user parameters can be found based on a
1
=
+
c a ⁄
S
TC1
TC Setup Part 1 - Obtaining the Magnetic Circuit Behaviour
user unnorm
user
T0
°C
user
,
user
-2
10
(
. Using these settings leads to a unity sensitivity at 0 °C.
T T0
–
=
(
0
T
°C and normalizing the linear and quadratic terms
k
user
Temperature Coefficient Setup Guide
)
can then be found as:
)
+
TC2
user
(
TC1
T T0
–
user
®
user
,
Excel
y x ( )
TC2
)
2
), we can see that the
Rev 1.1, 2008-10-30
user
®
=
, enter the points
a
+
and the Excel
bx
TLE4998
+
T
cx
nd
k
2
order
while
. By
(10)
(11)
(12)
(9)