DATA SHEET
HAL810
Step 2: Calculation of DCOQ and DCSensitivity
2.4. Calibration of the Angle Sensor
The calibration points 1 and 2 can be set inside the
specified range. The corresponding values for DC1
and DC2 result from the application requirements.
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°
Min-Duty ≤ DC1,2 ≤ Max-Duty
– temperature coefficient of the magnet: −500 ppm/K
For highest accuracy of the sensor, calibration points
near the minimum and maximum input signal are rec-
ommended. The difference of the duty cycle between
calibration point 1 and calibration point 2 should be
more than 70%.
Set the system to calibration point 1 and read the reg-
ister ADC-READOUT. The result is ADC-Readout1.
Now, set the system to calibration point 2, read the
register ADC-READOUT, and get ADC-Readout2.
With these readouts and the nominal duty cycles DC1
and DC2, for the calibration points 1 and 2, respec-
tively, the values for DCSensitivity and DCOQ are cal-
culated as follows:
DC2 − DC1
2048
DCSensitivity =
*
100%
%
ADC-Readout2 − ADC-Readout1
100
ADC-Readout1 * DCSensitivity * 100%
2048
DC
= DC
−
1
Max-Duty = 95%
OQ
Output
Calibration Point 1
Duty
Cycle
80
This calculation has to be done individually for each
sensor.
Next, write and store the calculated values for DCSen-
sitivity and DCOQ into the IC for adjusting the sensor.
60
40
The sensor is now calibrated for the customer applica-
tion. However, the programming can be changed
again and again if necessary.
20
Step 3: Locking the Sensor
Min-Duty = 5%
Calibration Point 2
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.
0
°
30
–30 –20 –10
0
10
20
Angle
Fig. 2–7: Example for output characteristics
Warning: This register cannot be reset!
Micronas
Feb. 6, 2009; DSH000034_003EN
11
MICRONAS [ MICRONAS ]
