DATA SHEET
2.3.2. Calibration of the Angle Sensor
The following description explains the calibration pro-
cedure using an angle sensor as an example. The
required output characteristic is shown in Fig. 2–7.
– the angle range is from
−25°
to 25°
– temperature coefficient of the magnet:
−500
ppm/K
Step 2: Calculation of V
OQ
and Sensitivity
The calibration points 1 and 2 can be set inside the
specified range. The corresponding values for V
OUT1
and V
OUT2
result from the application requirements.
Low clamping voltage
≤
V
OUT1,2
≤
High clamping voltage
For highest accuracy of the sensor, calibration points
near the minimum and maximum input signal are rec-
ommended. The difference of the output voltage
between calibration point 1 and calibration point 2
should be more than 3.5 V.
Set the system to calibration point 1 and read the reg-
ister ADC-READOUT. The result is the value ADC-
READOUT1.
Now, set the system to calibration point 2, read the
register ADC-READOUT again, and get the value
ADC-READOUT2.
With these values and the target values V
OUT1
and
V
OUT2
, for the calibration points 1 and 2, respectively,
the values for Sensitivity and V
OQ
are calculated as:
Sensitivity =
V
OUT1
−
V
OUT2
ADC-READOUT1
−
ADC-READOUT2
*
2048
V
DD
V
5
Clamp-high = 4.5 V
Calibration point 1
VOUT
4
3
2
1
V
OQ
= V
OUT1
−
ADC-READOUT1 * Sensitivity * V
DD
2048
Clamp-low = 0.5 V
Calibration point 2
0
−30
−20
−10
0
10
20
Angle
30
°
This calculation has to be done individually for each
sensor.
Next, write the calculated values for Sensitivity and
V
OQ
into the IC for adjusting the sensor.
The sensor is now calibrated for the customer applica-
tion. However, the programming can be changed
again and again if necessary.
Fig. 2–7:
Example for output characteristics
Step 3: Locking the Sensor
The last step is activating the LOCK function with the
“LOCK” command. Please note that the LOCK function
becomes effective after power-down and power-up of
the Hall IC. The sensor is now locked and does not
respond to any programming or reading commands.
Warning: This register cannot be reset!
Micronas
Feb. 7, 2006; 6251-537-3DS
11
MICRONAS [ MICRONAS ]
