Table of Contents
Advertisement
6
Calibration of TLE4997 Output Characteristic
In a position sensing application, the maximum and minimum magnetic field sensed by the TLE4997 depends on
the employed permanent magnet and the movement range covered by the application. To achieve the maximum
possible accuracy in such applications, it is recommended to adapt the output characteristic of the TLE4997 so
the possible analog output range is matched to the magnetic input range that is available in the application.
6.1
Two-Point Calibration Procedure
Position sensor modules are typically subject to production variations in terms of magnet strength and magnet
position, therefore it is recommended to do a two-point calibration of the TLE4997 after assembly of each module
to achieve the desired output characteristics independent of such production variations.
In order to configure an application specific output-characteristic, a two-point calibration procedure is used, where
the IC-internal representation HCAL (compare
defined positions and the output offset and gain are adjusted accordingly. This procedure is illustrated in
Figure
6-1.
Max Output
(100%)
Min Output
(0%)
Figure 6-1 Schematic of Two-Point Calibration
The value VDAC is calculated in the TLE4997 with the configured offset (OS) and gain (G) value according to
Equation
(6.1).
(
G 16384
--------------------------------------------------- -
VDAC
=
For the two-point calibration, the following procedure is used:
1. Select two reference positions Pos1 and Pos2 for the moveable magnet in the application module. For
maximum accuracy of the calibration routine it is recommended that the desired signal difference between
these positions is at least half the full signal range.
2. Chose the desired output signals VDAC1' and VDAC2' which should correspond to positions Pos1 and Pos2
in the final configuration.
3. Fix the application module in position Pos1 and read the HCAL register via the programming interface. This
value is HCAL1.
4. Fix the application module in position Pos2 and read the HCAL register via the programming interface. This
value is HCAL2.
User's Manual
VDAC 1'
~V
out1
VDAC2'
~V
0
Pos 2 (B
)
2
~HCAL2
application movement range
) HCAL
⋅
–
OS 16384
+
32768
Calibration of TLE4997 Output Characteristic
Figure
2-1) of the Hall measurement value is evaluated at two
VDAC
V
[%]
~
out
out2
Pos 1 (B
)
1
~HCAL1
–
34
User's Manual
after 2-point
calibration
before 2-point
calibration
Position
~ Magnetic Flux (mT)
v01_01, 2019-08
TLE4997
(6.1)
Advertisement
Table of Contents
