MicroSystems Inc.'s new line of user-programmable, two-wire, unipolar,
Hall-effect switches complement its existing family of devices used in seat
belt buckle, seat position and shift selector (PRNDL) applications. Allegro's A1190/2/3 family consists of
two-wire, unipolar, Hall-effect switches, which can be trimmed by the user at
end-of-line to optimize magnetic switchpoint accuracy in the application. These
devices are produced on the Allegro advanced BiCMOS wafer fabrication process,
which implements a patented high frequency, 4-phase, chopper-stabilization
technique. This technique achieves magnetic stability over the full operating
temperature range, and eliminates offsets inherent in devices with a single
Hall element that are exposed to harsh application environments.
A119x family has a number of automotive applications. These include: sensing
seat track position, seat belt buckle presence, hood/trunk latching and shift
selector position. Two-wire unipolar switches are advantageous in
cost-sensitive applications because they require one less wire for operation
versus the more traditional open-collector output switches. Additionally, the
system designer inherently gains diagnostics, because there is always output
current flowing, which should be in either of two narrow ranges. Any current
level not within these ranges indicates a fault condition.
upgrade to this family of two-wire switches is the on-chip transient protection
and a zener clamp to protect against over-voltage conditions on the supply
line. This improved high voltage transient protection allows these devices to
survive ISO 7637-2 and 40 V load dump for <0.5 secs with minimal,
and sometime no, protection from discrete components. The ESD protection has
been enhanced, such that these devices are capable of handling transients up to
8 kV Human Body Model (HBM). The A1190, A1192 and A1193 are offered in a
SOT-23W style, miniature low profile package (LH) for surface-mount
applications. All devices are priced at $0.56 in quantities of 1,000.
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