DATA SHEET
HAL856
operating range of the A/D converter is from
−30
mT...
+30 mT up to
−150
mT... +150 mT.
During further processing, the digital signal is calcu-
lated based on the values of slope, shift, and the
defined output characteristic. The result is converted to
the different digital output formats (PWM and
Biphase-M) and transmitted by a current source out-
put.
The DIGITAL OUTPUT value at any given magnetic
field depends on the settings of the magnetic field
range, the low-pass filter, TC, TCSQ values and the
programmed output characteristic. The DIGITAL
OUTPUT range is min. 0 to max. 4095.
2.2. Digital Signal Processing and EEPROM
The DSP is the major part of this sensor and performs
the signal conditioning. The parameters for the DSP
are stored in the EEPROM registers. The details are
shown in Fig. 2–3 on page 8.
Terminology:
SLOPE:
Slope:
name of the register or register value
name of the parameter
The EEPROM registers consist of three groups:
Group 1
contains the registers for the adaption of the
sensor to the magnetic system: MODE for selecting
the magnetic field range and filter frequency, TC and
TCSQ for the temperature characteristics of the mag-
netic sensitivity.
The parameters SLOPE and SHIFT are used for the
individual calibration of the sensor in the magnetic cir-
ucit.
– The parameter Shift corresponds to the output sig-
nal at B = 0 mT.
– The parameter Slope defines the magnetic sensitiv-
ity.
Group 2
contains the registers for defining the output
characteristics: OUTPUT FORMAT, OUTPUT PERIOD
or OUTPUT BITTIME, SLEW RATE, OUTPUT CHAR-
ACTERISTIC, LOW CURRENT and HIGH CURRENT.
The shape of the output signal is determined by the
output characteristic, which, in turn, is defined by the
32 setpoints of the sensor. A value for each of the set-
points must be defined. The setpoints are distributed
evenly along the magnetic field axis allowing linear
interpolation between the 32 setpoints (see Fig. 2–4).
Group 3
contains the PARTNUMBER, the Micronas
registers, and LOCK for the locking of all registers.
After locking, the PARTNUMBER register is only avail-
able in Biphase-M output mode. The Micronas regis-
ters are programmed and locked during production
and are read-only for the customer. These registers
are used for oscillator frequency trimming and several
other special settings.
An external magnetic field generates a Hall voltage on
the Hall plate. The A/D-converter converts the ampli-
fied positive or negative Hall voltage (operates with
magnetic north and south poles at the branded side of
the package) to a digital value. The digital signal is
filtered in the internal low-pass filter and manipulated
according to the settings stored in the EEPROM. The
digital value after signal processing is readable in the
DIGITAL OUTPUT register. Depending on the pro-
grammable magnetic range of the Hall IC, the
Note:
During application design, it should be taken
into consideration that DIGITAL OUTPUT
should not saturate in the operational range of
the specific application.
%
100
90
PWM 80
70
60
50
40
30
HAL 856
Logarithmic
20
10
0
0
4
8
12
16
20
Linear
Sine
24
28
32
Logarithmic
Setpoint
Linear
Fig. 2–4:
Example for different
Sine
output characteristics
Micronas
March 23, 2010; DSH000142_002EN
9
MICRONAS [ MICRONAS ]
