A1220, A1221, and A1222
Chopper Stabilized Precision Hall Effect Latches
Features and Benefits
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Symmetrical latch switchpoints
Resistant to physical stress
Superior temperature stability
Output short-circuit protection
Operation from unregulated supply down to 3 V
Reverse battery protection
Solid-state reliability
Small package sizes
Description
The A1220, A1221, and A1222 Hall-effect sensor ICs are
extremely temperature-stable and stress-resistant devices
especially suited for operation over extended temperature ranges
to 150°C. Superior high-temperature performance is made
possible through dynamic offset cancellation, which reduces the
residual offset voltage normally caused by device overmolding,
temperature dependencies, and thermal stress. Each device
includes on a single silicon chip a voltage regulator, Hall-voltage
generator, small-signal amplifier, chopper stabilization, Schmitt
trigger, and a short-circuit protected open-collector output to
sink up to 25 mA. A south pole of sufficient strength turns the
output on. A north pole of sufficient strength is necessary to
turn the output off.
An onboard regulator permits operation with supply voltages
of 3 to 24 V. The advantage of operating down to 3 V is that
the device can be used in 3-V applications or with additional
external resistance in series with the supply pin for greater
protection against high voltage transient events.
Packages:
3-pin SOT23W (suffix LH)
3-pin SIP (suffix UA)
Two package styles provide magnetically optimized packages
for most applications. Package type LH is a modified 3-pin
SOT23W surface mount package while UA is a three-pin ultra-
mini SIP for through hole mounting. Both packages are lead
(Pb) free, with 100% matte tin plated leadframes.
Not to scale
Functional Block Diagram
VCC
Regulator
To All Subcircuits
Amp
Sample and Hold
Dynamic Offset
Cancellation
Low-Pass
Filter
VOUT
Control
Current Limit
GND
A1220-DS, Rev. 8
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
