A1391 and A1392
Micro Power 3 V Linear Hall Effect Sensor with Tri-State Output and User-Selectable Sleep Mode
Application Circuit with User-Configurable Ratiometry
In figures 4 and 5, the microprocessor supply voltage determines
the ratiometric performance of the A1391/A1392 output signal.
As in the circuits shown in figures 2 and 3, the device is powered
by the Vbat2 supply, but in this case, ratiometry is determined by
the microprocessor supply, Vbat1.
The ¯ ¯ ¯ ¯ ¯ pin is triggered by the output logic signal from the
SLEEP
¯¯¯
microprocessor in figure 5, while in figure 4, the ¯ ¯ ¯ ¯ ¯ pin is
SLEEP
¯¯¯
connected to the device power supply pin. Therefore, the device
as configured in figure 4 is constantly in active mode, while
the device as confiugred in figure 5 can be periodically toggled
between the active and sleep modes.
The capacitor C
filter
is optional, and can be used to prevent pos-
sible noise transients from the microprocessor supply reaching
the device reference pin, VREF.
It is
strongly recommended
that an external bypass capacitor
be connected, in close proximity to the A1391/A1392 device,
between the VCC and GND pins of the device to reduce both
external noise and noise generated by the chopper-stabilization
circuits inside of the A1391/A1392.
C
filter
Vbat 1
Supply pin
C
bypass
Vbat2
VCC
OUT
VREF
SLEEP
Micro- I/O
processor
I/O
A1391/A1392
GND
GND
Figure 4. Application circuit showing ratiometry of V
REF
. Sleep mode is disabled and the VREF
pin is tied to the microprocessor supply.
C
filter
Vbat1
Supply pin
C
bypass
Vbat2
VCC
OUT
VREF
SLEEP
Micro- I/O
processor
I/O
A1391/A1392
GND
GND
Figure 5. Application circuit showing device reference pin, VREF, tied to microprocessor supply. The device
sleep mode also is controlled by the microprocessor.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
12
A1391-DS
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
