DATA SHEET
HAL880
2.3. Calibration Procedure
2.3.1. General Procedure
Step 3: Define Calibration Points
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.
For calibration in the system environment, the applica-
tion kit from Micronas is recommended. It contains the
hardware for the generation of the serial telegram for
programming (Programmer Board Version 5.1) and the
corresponding software (PC880) for the input of the
register values.
Lowclampingvoltage ≤ VOUT1,2 ≤ Highclampingvoltage
For highest accuracy of the sensor, calibration points
near the minimum and maximum input signal are
recommended. The difference of the output voltage
between calibration point 1 and calibration point 2
should be more than 3.5 V.
For the individual calibration of each sensor in the cus-
tomer application, a two-point adjustment is recom-
mended. The calibration has be done as follows:
Step 1: Input of the registers which need not be
adjusted individually
Step 4: Calculation of VOQ and Sensitivity
The magnetic circuit, the magnetic material with its
temperature characteristics, the filter frequency, the
output mode and the GP register value are given for
this application. Therefore, the values of the following
registers should be identical for all sensors of the
customer application.
Set the system to calibration point 1 and read the reg-
ister D/A-READOUT. The result is the value
D/A-READOUT1.
Now, set the system to calibration point 2, read the
register D/A-READOUT again, and get the value
D/A-READOUT2.
– FILTER
(according to the maximum signal frequency)
With these values, and the target values VOUT1 and
– RANGE
VOUT2, for the calibration points 1 and 2, respectively,
(according to the maximum magnetic field at the
sensor position)
the values for Sensitivity and VOQ are calculated as:
– OUTPUTMODE
1
2
(Vout2 – Vout1)
D/A-Readout2 – D/A-Readout1
16384
5
-- ---------------------------------------------------------------------------------- --------------
Sensitivity =
×
×
– TC, TCSQ, and TC-RANGE
(depends on the material of the magnet and the
other temperature dependencies of the application)
– GP
1
16
Vout2 × 16384
(if the customer wants to store own production infor-
mation, it is not necessary to change this register)
-----
------------------------------------
VOQ
=
×
–
5
5
1024
-----------
[(D/A-Readout2 – 8192) × Sensitivity × 2] ×
As the clamping voltages are given, they have an influ-
ence on the D/A-readout value and therefore have to
be set after the adjustment process.
This calculation has to be done individually for each
sensor.
Write the appropriate settings into the HAL880
registers.
Next, write the calculated values for Sensitivity and
VOQ into the IC for adjusting the sensor. At that time, it
Step 2: Initialize DSP
is also possible to store the application specific values
for Clamp-Low and Clamp-High into the sensors
EEPROM.
As the D/A-READOUT register value depends on
the
settings
of SENSITIVITY, VOQ, and
CLAMP-LOW/HIGH, these registers have first to be
initialized with defined values:
– VOQINITIAL = 2.5 V
– SensitivityINITIAL = 0.5
– Clamp-Low = 0 V
– Clamp-High = 4.999 V
Micronas
Feb. 23, 2009; DSH000152_001EN
11
MICRONAS [ MICRONAS ]
