DATA SHEET
HAL880
4. Application Notes
4.2. Use of two HAL880 in Parallel
4.1. Application Circuit
Two different HAL880 sensors which are operated in
parallel to the same supply and ground line can be
programmed individually. In order to select the IC
which should be programmed, both Hall ICs are
inactivated by the “Deactivate” command on the com-
mon supply line. Then, the appropriate IC is activated
by an “Activate” pulse on its output. Only the activated
sensor will react to all following read, write, and pro-
gram commands. If the second IC has to be pro-
grammed, the “Deactivate” command is sent again
and the second IC can be selected.
For EMC protection, it is recommended to connect one
ceramic 4.7 nF capacitor each between ground and
the supply voltage, respectively the output voltage pin.
In addition, the input of the controller unit should be
pulled-down with a 10 kΩ resistor and a ceramic
4.7 nF capacitor.
Please note that during programming, the sensor will
be supplied repeatedly with the programming voltage
of 12.5 V for 100 ms. All components connected to the
VDD line at this time must be able to resist this voltage.
Note: The multi-programming of two sensors works
only if the outputs of the two sensors are pulled
to GND with a 10 kΩ pull-down resistor.
V
DD
V
DD
OUT
HAL880
μC
4.7 nF
OUT A & Select A
OUT B & Select B
4.7 nF
4.7 nF
10 kΩ
GND
HAL880
HAL880
Sensor A
Sensor B
10 nF
Fig. 4–1: Recommended application circuit
4.7 nF
4.7 nF
GND
Fig. 4–2: Parallel operation of two HAL880
Micronas
Feb. 23, 2009; DSH000152_001EN
23
MICRONAS [ MICRONAS ]
