A1121 Datasheet, PDF (1/13 Pages) Allegro MicroSystems – Chopper Stabilized Precision Hall Effect Switches

A1120, A1121, and A1125
Chopper Stabilized Precision Hall Effect Switches
Features and Benefits
▪ Unipolar switchpoints
▪ Resistant to physical stress
▪ Superior temperature stability
▪ Output short-circuit protection
▪ Operation from unregulated supply
▪ Reverse battery protection
▪ Solid-state reliability
▪ Small package sizes
Packages:
3-pin SOT23W (suffix LH)
Not to scale
3-pin SIP (suffix UA)
Description
The A1120, A1121, and A1125 Hall-effect, unipolar switches
are extremely temperature-stable and stress-resistant sensor
ICs, 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-drain output to sink up to 25 mA.
An on-board 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.
For the A1120 and A1121, a south pole of sufficient strength
turns the output on. Removal of the magnetic field turns the
output off. The A1125 is complementary, in that for these
devices, a south pole turns the A1125 output off, and removal
of the magnetic field turns the output on.
Two package styles provide a magnetically optimized package
for most applications. Package type LH is a modified SOT23W,
surface mount package, while UA is a three-lead ultra-mini SIP
for through-hole mounting. Each package type is lead (Pb) free
(suffix, –T), with a 100% matte tin plated leadframe.
Functional Block Diagram
VCC
Amp
Regulator
Low-Pass
Filter
To All Subcircuits
Control
Current Limit
VOUT
GND
A1120-DS, Rev. 11