HAL800 Datasheet, PDF (8/24 Pages) Micronas – Programmable Linear Hall Effect Sensor

HAL 800
Range
The RANGE bits are the two lowest bits of the MODE
register; they define the magnetic field range of the
A/D converter.
RANGE
0
1
2
3
Magnetic Field Range
−30 mT...30 mT
−75 mT...75 mT
−90 mT...90 mT
−150 mT...150 mT
Filter
The FILTER bit is the highest bit of the MODE register;
it defines the −3 dB frequency of the digital low pass fil-
ter
FILTER
0
1
−3 dB Frequency
2 kHz
500 Hz
TC and TCSQ
The temperature dependence of the magnetic sensitiv-
ity can be adapted to different magnetic materials in
order to compensate for the change of the magnetic
strength with temperature. The adaption is done by
programming the TC (Temperature Coefficient) and
the TCSQ registers (Quadratic Temperature Coeffi-
cient). Thereby, the slope and the curvature of the
magnetic sensitivity can be matched to the magnet
and the sensor assembly. As a result, the output volt-
age characteristic can be fixed over the full tempera-
ture range. The sensor can compensate for linear tem-
perature coefficients in the range from about -2900
ppm/K up to 700 ppm/K and quadratic coefficients
from about -5 ppm/K² to 5 ppm/K². Please refer to
Section 4.2. on page 17 for the recommended settings
for different linear temperature coefficients.
Sensitivity
The SENSITIVITY register contains the parameter for
the Multiplier in the DSP. The Sensitivity is programma-
ble between -4 and 4. For V_DD = 5 V the register can
be changed in steps of 0.00049. Sensitivity = 1 corre-
sponds to an increase of the output voltage by V_DD if
the ADC-READOUT increases by 2048.
For all calculations, the digital value from the magnetic
field of the A/D converter is used. This digital informa-
tion is readable from the ADC-READOUT register.
Sensitivity =
∆V_OUT * 2048
∆ADC-READOUT * V_DD
VOQ
The VOQ register contains the parameter for the
Adder in the DSP. V_OQ is the output voltage without
external magnetic field (B = 0 mT) and programmable
from − V_DD up to V_DD. For V_DD = 5 V the register can
be changed in steps of 4.9 mV.
Note: If V_OQ is programmed to a negative voltage, the
maximum output voltage is limited to:
V_OUTmax = V_OQ + V_DD
For calibration in the system environment, a 2-point
adjustment procedure (see Section 2.3.) is recom-
mended. The suitable Sensitivity and V_OQ values for
each sensor can be calculated individually by this pro-
cedure.
Clamping Voltage
The output voltage range can be clamped in order to
detect failures like shorts to V_DD or GND.
The CLAMP-LOW register contains the parameter for
the lower limit. The lower clamping voltage is program-
mable between 0 V and V_DD/2. For V_DD = 5 V the reg-
ister can be changed in steps of 2.44 mV.
The CLAMP-HIGH register contains the parameter for
the higher limit. The higher clamping voltage is pro-
grammable between 0 V and V_DD. For V_DD = 5 V in
steps of 2.44 mV.
LOCK
By setting this 1-bit register, all registers will be locked,
and the sensor will no longer respond to any supply
voltage modulation.
Warning: This register cannot be reset!
ADC-READOUT
This 14-bit register delivers the actual digital value of
the applied magnetic field before the signal process-
ing. This register can be read out and is the basis for
the calibration procedure of the sensor in the system
environment.
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