A1140/41/42/43
A1140-DS, Rev. 2 Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
AB SO LUTE MAX I MUM RAT INGS
Supply Voltage, VCC ..........................................28 V
Reverse-Supply Voltage, VRCC ........................–18 V
Magnetic Flux Density, B .........................Unlimited
Power Dissipation, PD............................ Graph, p. 5
Operating Temperature
Ambient, TA, Range E.................. –40ºC to 85ºC
Ambient, TA, Range L................ –40ºC to 150ºC
Maximum Junction, TJ(max)........................165ºC
Storage Temperature, TS.................. –65ºC to 170ºC
On-chip protection
Supply transient protection
Reverse-battery protection
On-board voltage regulator
3.5 to 24 V operation
Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall Effect Switches
Package LH, 3-pin SOT
Features and Benefits
The A1140, A1141, A1142, and A1143 devices are sensitive, two-wire, unipolar,
Hall effect switches that are factory-programmed at end-of-line to optimize mag-
netic switchpoint accuracy. These devices use a patented high frequency chop-
per-stabilization technique, produced using the Allegro advanced BiCMOS wafer
fabrication process, to achieve magnetic stability and to eliminate offset inherent
in single-element devices exposed to harsh application environments.
Commonly found in a number of automotive applications, these switches are
utilized to sense seat track position, seat belt buckle presence, hood/trunk latching,
and shift selector position. Two-wire unipolar switches, such as the
A1140/41/42/43 family, are particularly advantageous in price-sensitive applica-
tions because they require one less wire for operation than do switches with the
more traditional open-collector output. Additionally, the system designer inher-
ently 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. The A1140/41/42/43 family of switches also features
on-chip transient protection and a Zener clamp to protect against overvoltage
conditions on the supply line.
The output currents of the A1141 and A1143 switch HIGH in the presence of a
south (+) polarity magnetic field of sufficient strength, and switch LOW other-
wise, as in the presence of a weak field or a north (–) polarity field. The other two
devices in the family (A1140 and A1142) have an opposite output: the currents
switch LOW in the presence of a south-polarity magnetic field of sufficient
strength, and switch HIGH otherwise. The other differences in the switches are
their defined low current levels and magnetic switchpoints.
All versions are offered in two package styles. The LH is a SOT-23W, miniature
low-profile package for surface-mount applications. The UA is a three-lead ultra-
mini SIP for through-hole mounting. Each package is available in a lead (Pb) free
version (suffix, –T) with 100% matte tin plated leadframe. Field-programmable
versions also available: A1180, A1181, A1182, and A1183.
Package UA, 3-pin SIP
Chopper stabilization
Low switchpoint drift over operating
temperature range
Low sensitivity to stress
Factory programmed at end-of-line for
optimized switchpoints
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≈1:1