ADVANCE INFORMATION
HAL815
2. Functional Description
2.1. General Function
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 HAL 815 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 open-circuit detection provides a defined output
voltage if the VDD 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.
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.
HAL
815
V
DD
8
7
6
5
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
digital
analog
V
OUT
DD
GND
Fig. 2–1: Programming with VDD modulation
V
DD
Internally
stabilized
Supply and
Protection
Devices
Open-circuit,
Temperature
Dependent
Bias
Protection
Devices
Overvoltage,
Undervoltage
Detection
Oscillator
100 Ω
Digital
Signal
Processing
OUT
Switched
Hall Plate
A/D
Converter
D/A
Converter
Analog
Output
10 kΩ
EEPROM Memory
Supply
Level
Detection
Digital
Output
Lock Control
GND
Fig. 2–2: HAL 815 block diagram
Micronas
5
MICRONAS [ MICRONAS ]
