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.
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
鏗?/div>
ows in either of two narrowly-speci鏗乪d 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.
The output currents of the A1141 and A1143 switch
HIGH
in the presence of a south
polarity magnetic
鏗?/div>
eld of suf鏗乧ient strength; and switch
LOW
otherwise, including
when there is no signi鏗乧ant magnetic
鏗?/div>
eld present. The A1140 and A1142 have
inverted output current levels: switching
LOW
in the presence of a south polarity
magnetic
鏗?/div>
eld of suf鏗乧ient strength, and
HIGH
otherwise. The devices also differ in
their speci鏗乪d
LOW
current supply levels.
All family members are offered in two package styles: SOT-23W, a miniature low-
pro鏗乴e package for surface-mount applications (suf鏗亁
鈥揕H),
and TO-92, three-
lead ultra-mini Single Inline Package (SIP) for through-hole mounting
(suf鏗亁
鈥揢A).
Field-programmable versions are also available. Refer to: A1180, A1181, A1182,
and A1183.
Package LH, 3-pin SOT
3
1. VCC
2. No connection
3. GND
NC
1
2
Package UA, 3-pin SIP
1. VCC
2. GND
3. GND
1
2
PTCT
3
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
..........................................
28 V
Reverse-Supply Voltage, V
RCC
........................
鈥?8 V
Magnetic Flux Density, B .........................Unlimited
Operating Temperature
Ambient, T
A
, Range E..................
鈥?0潞C to 85潞C
Ambient, T
A
, Range L................
鈥?0潞C to 150潞C
Maximum Junction, T
J(max)
........................165潞C
Storage Temperature, T
S
..................
鈥?5潞C to 170潞C
Features and Bene鏗乼s
Chopper stabilization
Low switchpoint drift over operating tem-
perature range
Low stress sensitivity
Factory programmed at end-of-line for
optimized switchpoints
On-chip protection
Supply transient protection
Reverse-battery protection
On-board voltage regulator
3.5 V to 24 V operation
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ALLEGRO
1
2
3
4
5
6
7
8
9
10
11
