A1171
Micropower Ultrasensitive Hall Effect Switch
Features and Benefits
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1.65 to 3.5 V battery operation
Low supply current
High sensitivity, B
OP
typically 30 G (3.0 mT)
Operation with either north or south pole
Configurable unipolar or omnipolar magnetic sensing
Complementary, push-pull outputs
Chopper stabilized
▫ Superior temperature stability
▫ Extremely low switchpoint drift
▫ Insensitive to physical stress
▪ Solid state reliability
▪ Small size
Description
The A1171 integrated circuit is an ultrasensitive, Hall effect
switch with latched digital outputs and either unipolar or
omnipolar magnetic actuation. It features operation at low
supply currents and voltages, making it ideal for battery-
operated electronics. The low operating supply voltage,
1.65 to 3.5 V, and unique clocking algorithm assist in reducing
the average operating power consumption. For example, the
power requirement is less than 15 μW with a 2.75 V supply.
Unlike more traditional Hall effect switches, the A1171 allows
the user to configure how the device is magnetically actuated.
Under default conditions the device activates output switching
with either a north or south polarity magnetic field of sufficient
strength. The magnetic actuation can be set via an external
selection pin to operate in a unipolar mode, switching only on
a north or south polarity but not both. Furthermore, the output
of the A1171 can be configured to switch either off or on in the
absence of any significant magnetic field. Lastly, the A1171
has two push-pull output structures.
This polarity-independence, as well as the minimal power
requirements, allows the A1171 to easily replace reed switches,
Package: 6 pin DFN/MLP (suffix EW)
Not to scale
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Functional Block Diagram
VDD
Clock / Logic
Sample and Hold
and Averaging
Dynamic Offset
Cancellation
Low-Pass
Filter
Latch
Logic
VOUTPS
Amp
Latch
VOUTPN
GND
1171-DS
SELECT
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
