DATA SHEET
HAL815
Step 2: Calculation of VOQ and Sensitivity
2.3.2. Calibration of the Angle Sensor
The calibration points 1 and 2 can be set inside the
specified range. The corresponding values for VOUT1
and VOUT2 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°
Low clamping voltage ≤ VOUT1,2 ≤ High clamping voltage
– 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 output voltage
between calibration point 1 and calibration point 2
should be more than 3.5 V.
V
5
Set the system to calibration point 1 and read the reg-
ister ADC-READOUT. The result is the value ADC-
READOUT1.
Clamp-high = 4.5 V
Calibration point 1
V
OUT
4
Now, set the system to calibration point 2, read the
register ADC-READOUT again, and get the value
ADC-READOUT2.
3
2
With these values and the target values VOUT1 and
VOUT2, for the calibration points 1 and 2, respectively,
the values for Sensitivity and VOQ are calculated as:
V
− V
OUT2
OUT1
2048
Sensitivity =
*
V
ADC-READOUT1 − ADC-READOUT2
DD
1
ADC-READOUT1 * Sensitivity * V
Clamp-low = 0.5 V
DD
V
= V
−
OUT1
OQ
2048
Calibration point 2
0
−30 −20 −10
This calculation has to be done individually for each
sensor.
0
10
20
Angle
30
°
Next, write the calculated values for Sensitivity and
VOQ into the IC for adjusting the sensor.
Fig. 2–7: Example for output characteristics
The sensor is now calibrated for the customer applica-
tion. However, the programming can be changed
again and again if necessary.
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 ]
