PRELIMINARY DATA SHEET
HAL805
Micronas
5
2. Functional Description
2.1. General Function
The HAL 805 is a monolithic integrated circuit which
provides an output voltage proportional to the mag-
netic flux through the Hall plate and proportional to the
supply voltage (ratiometric behavior).
The external magnetic field component perpendicular
to the branded side of the package generates a Hall
voltage. The Hall IC is sensitive to magnetic north and
south polarity. This voltage is converted to a digital
value, processed in the Digital Signal Processing Unit
(DSP) according to the settings of the EEPROM regis-
ters, converted to an analog voltage with ratiometric
behavior, and stabilized by a push-pull output transis-
tor stage. The function and the parameters for the DSP
are explained in Section 2.2. on page 7.
The setting of the LOCK register disables the program-
ming of the EEPROM memory for all time. This regis-
ter cannot be reset.
As long as the LOCK register is not set, the output
characteristic can be adjusted by programming the
EEPROM registers. The IC is addressed by modulat-
ing the supply voltage (see Fig. 2
–
1). In the supply
voltage range from 4.5 V up to 5.5 V, the sensor gener-
ates an analog output voltage. After detecting a com-
mand, the sensor reads or writes the memory and
answers with a digital signal on the output pin. The
analog output is switched off during the communica-
tion.
Several sensors in parallel to the same supply and
ground line can be programmed individually. The
selection of each sensor is done via its output pin.
The open-circuit detection provides a defined output
voltage if the V
DD
or GND line is broken. Internal tem-
perature compensation circuitry and the choppered off-
set compensation enables operation over the full tem-
perature range with minimal changes in accuracy and
high offset stability. The circuitry also rejects offset
shifts due to mechanical stress from the package. The
non-volatile memory consists of redundant EEPROM
cells. In addition, the sensor IC is equipped with
devices for overvoltage and reverse-voltage protection
at all pins.
Fig. 2
–
1:
Programming with V
DD
modulation
Fig. 2
–
2:
HAL 805 block diagram
V
O
5
6
7
8
V
D
HAL
805
V
DD
GND
OUT
analog
V
DD
digital
Internally
stabilized
Supply and
Protection
Devices
Temperature
Dependent
Bias
Oscillator
Switched
Hall Plate
100
Digital
Signal
Processing
D/A
Converter
Analog
Output
OUT
V
DD
GND
Supply
Level
Detection
EEPROM Memory
Lock Control
Digital
Output
Protection
Devices
A/D
Converter
10 k
Open
Circuit
Detection