TLE4997 Datasheet, PDF (15/36 Pages) Infineon Technologies AG – Programmable Linear Hall Sensor for Industrial Use

TLE4997I
Electrical and Magnetic Parameters
Ratiometry
The linear Hall sensor works like a potentiometer. The output voltage is proportional to
the supply voltage. The division factor depends on the magnetic field strength. This
behavior is called “ratiometric”’.
The supply voltage V_DD should be used as the reference for the A/D Converter of the
microcontroller. In this case, variations of V_DD are compensated.
The ratiometry error is defined as follows:
E_RAT
=



V_{-----O----U---T---}(_---V_{----D----D----})
V_DD
–
-^V----^O---^U--5--^T--V-⁽---5---V-----^{)}
× 100
%
The ratiometry error band displays as a “Butterfly Curve”.
%
n
E_RAT
1
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
-1
-n
4
5
Figure 4 Ratiometry Error Band
6
7
V_DD
V
The error band in the extended V_DD range below 4.5 V and above 5.5 V is defined as
shown in Figure 4. In the range from 6 to 7 Volts, the error band depends on the output
signal. For V_OUT lower than 20% of V_DD, the value for n is 2%. For V_OUT higher than 80%
of V_DD, the value for n is 5%. And if V_OUT is kept (clamped) in between, the value for n
is 1%.
Note: Take care of possible voltage drops on the V_DD and V_OUT line degrading the
result. Ideally, both values are acquired and their ratio is calculated to gain the
highest accuracy. This method should be used especially during calibration.
Data Sheet
15
V 1.0, 2007-06