2. Functional Description
2.1. General Function
The HAL815 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 8.
The setting of the LOCK register disables the program-
ming of the EEPROM memory for all time. This regis-
ter cannot be reset.
V
DD
(V)
DATA SHEET
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.
HAL
815
8
7
6
5
V
DD
V
OUT
(V)
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 gen-
erates an analog output voltage. After detecting a
command, the sensor reads or writes the memory and
answers with a digital signal on the output pin. The
V
DD
GND
OUT
digital
analog
Fig. 2–1:
Programming with V
DD
modulation
V
DD
Internally
stabilized
Supply and
Protection
Devices
Temperature
Dependent
Bias
Oscillator
Open-circuit,
Overvoltage,
Undervoltage
Detection
Protection
Devices
Switched
Hall Plate
A/D
Converter
Digital
Signal
Processing
D/A
Converter
Analog
Output
100
Ω
OUT
EEPROM Memory
Supply
Level
Detection
Lock Control
GND
Digital
Output
10 kΩ
Fig. 2–2:
HAL815 block diagram
6
Feb. 7, 2006; 6251-537-3DS
Micronas
MICRONAS [ MICRONAS ]
