A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall-Effect Switches
The A1140, A1141, A1142, and A1143 devices are sensitive, two-wire, unipo-
lar, Hall effect switches that are factory-programmed at end-of-line to optimize
magnetic switchpoint accuracy. These devices are produced on the Allegro
MicroSystems advanced BiCMOS wafer fabrication process, which implements a
patented, high-frequency, chopper-stabilization technique that achieves magnetic
stability and eliminates the offsets that are inherent in single-element devices
exposed to harsh application environments. Commonly found in a number of
automotive applications, the A1140-43 family of devices are utilized to sense: seat
track position, seat belt buckle presence, hood/trunk latching, and shift selector
position.
Package LH, 3-pin SOT
3
1. VCC
2. No connection
3. GND
NC
2
1
Two-wire unipolar switches are particularly advantageous in price-sensitive appli-
cations, because they require one less wire than the more traditional open-collec-
tor output switches. Additionally, the system designer gains inherent diagnostics
because output current normally flows in either of two narrowly-specified ranges.
Any output current level outside of these two ranges is a fault condition. The
A1140-43 family of devices also features on-chip transient protection, and a Zener
clamp to protect against overvoltage conditions on the supply line.
Package UA, 3-pin SIP
PTCT
1. VCC
2. GND
3. GND
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 otherwise, including
when there is no significant magnetic field present. The A1140 and A1142 have
inverted output current levels: switching LOW in the presence of a south polarity
magnetic field of sufficient strength, and HIGH otherwise. The devices also differ in
their specified LOW current supply levels.
1
2
3
All family members are offered in two package styles: SOT-23W, a miniature low-
profile package for surface-mount applications (suffix –LH), and TO-92, three-
lead ultra-mini Single Inline Package (SIP) for through-hole mounting
(suffix –UA).
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC ..........................................28 V
Reverse-Supply Voltage, VRCC ........................–18 V
Magnetic Flux Density, B .........................Unlimited
Operating Temperature
Field-programmable versions are also available. Refer to: A1180, A1181, A1182,
and A1183.
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
Features and Benefits
ꢀChopper stabilization
ꢀOn-chip protection
ꢀLow switchpoint drift over operating tem- ꢀSupply transient protection
perature range
ꢀReverse-battery protection
ꢀLow stress sensitivity
ꢀOn-board voltage regulator
ꢀFactory programmed at end-of-line for
optimized switchpoints
ꢀ3.5 V to 24 V operation
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140-DS