HAL824 View Datasheet(PDF) - Micronas

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HAL824

High-Precision Programmable Linear Hall-Effect Sensor

Micronas 

DATA SHEET

HAL 82x

2.3. Calibration Procedure

2.3.1. General Procedure

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 (PC824 and PC825) for the

input of the register values.

For the individual calibration of each sensor in the cus-

tomer application, a two point adjustment is recom-

mended. The calibration shall be done as follows:

Step 1: Input of the registers which need not be

adjusted individually

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 cus-

tomer application.

– FILTER

(according to the maximum signal frequency)

– RANGE

(according to the maximum magnetic field at the

sensor position)

– OUTPUTMODE

– TC, TCSQ and TC-RANGE

(depends on the material of the magnet and the

other temperature dependencies of the application)

– GP

(if the customer wants to store own production infor-

mation. It is not necessary to change this register)

As the clamping voltages are given. They have an

influence on the D/A-Readout value and have to be set

therefore after the adjustment process.

Write the appropriate settings into the HAL82x regis-

ters.

Step 2: Initialize DSP

As the D/A-READOUT register value depends on

the settings of SENSITIVITY, VOQ and CLAMP-

LOW/HIGH, these registers have to be initialized

with defined values, first:

– VOQINITIAL = 2.5 V

– SensitivityINITIAL = 0.5

– Clamp-Low = 0 V

– Clamp-High = 4.999 V

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.

Lowclampingvoltage ≤ VOUT1,2 ≤ Highclampingvoltage

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.

Step 4: Calculation of VOQ and Sensitivity

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.

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:

Sensitivity

=

1--

2

×

(---D----/--A-------R----e-(--a-V--d--o-o--u-u--t-t-22-----––----VD----o-/-A--u----t--R1----)e--a---d---o---u---t--1---)

×

1---6---3----8---4-

5

VOQ

=

--1---

16

×

V-----o---u---t--2-----×-----1---6---3---8---4-

5

–

[(D/A-Readout2 – 8192) × Sensitivity × 2]

×

-----5------

1024

This calculation has to be done individually for each

sensor.

Next, write the calculated values for Sensitivity and

VOQ into the IC for adjusting the sensor. At that time it

is also possible to store the application specific values

for Clamp-Low and Clamp-High into the sensors

EEPROM.

Micronas

Feb. 3, 2009; DSH000143_003EN

11

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