HAL880
DATA SHEET
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 HAL880 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 and non-
redundant EEPROM cells. The non-redundant
EEPROM cells are only used to store production
information inside the sensor. 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 8.
The setting of the LOCK register disables the program-
ming of the EEPROM memory for all time. This regis-
ter cannot be reset.
HAL
880
VDD
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 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
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
Digital
Signal
Processing
OUT
Switched
Hall Plate
A/D
Converter
D/A
Converter
Analog
Output
EEPROM Memory
Open-Circuit
Detection
Lock Control
GND
Fig. 2–2: HAL880 block diagram
6
Feb. 23, 2009; DSH000152_001EN
Micronas
MICRONAS [ MICRONAS ]
