A1120, A1121, A1122, and A1125
Chopper Stabilized Precision Hall Effect Switches
Features and Benefits
Description
▪ Unipolar switchpoints
The A1120, A1121, A1122, 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,whichreducestheresidualoffsetvoltagenormally
causedbydeviceovermolding,temperaturedependencies,and
thermal stress.
▪ Resistant to physical stress
▪ Superior temperature stability
▪ Output short-circuit protection
▪ Operation from unregulated supply
▪ Reverse battery protection
▪ Solid-state reliability
▪ Small package sizes
Eachdeviceincludesonasinglesiliconchipavoltageregulator,
Hall-voltage generator, small-signal amplifier, chopper
stabilization, Schmitt trigger, and a short-circuit protected
open-drain output to sink up to 25 mA.
Packages:
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, A1121, and A1122, 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.
3-pin SOT23W (suffix LH)
3-pin SIP (suffix UA)
Not to scale
Twopackagestylesprovideamagneticallyoptimizedpackage
formostapplications.PackagetypeLHisamodifiedSOT23W,
surfacemountpackage,whileUAisathree-leadultra-miniSIP
forthrough-holemounting. Eachpackagetypeislead(Pb)free
(suffix, –T), with a 100% matte tin plated leadframe.
Functional Block Diagram
VCC
Regulator
To All Subcircuits
VOUT
Low-Pass
Filter
Amp
Control
Current Limit
GND
A1120-DS, Rev. 12