A1184
A1184-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, V
CC
..........................................28 V
Reverse-Supply Voltage, V
RCC
........................–18 V
Magnetic Flux Density, B .........................Unlimited
Operating Temperature
Ambient, T
A
, Range E..................–40ºC to 85ºC
Ambient, T
A
, Range L................–40ºC to 150ºC
Maximum Junction, T
J(max)
........................165ºC
Storage Temperature, T
S
..................–65ºC to 170ºC
On-chip protection
null Supply transient protection
null Reverse-battery protection
null On-board voltage regulator
null 3.5 V to 24 V operation
Standard Two-Wire Field-Programmable Chopper-Stabilized
Unipolar Hall-Effect Switches
Package LH, 3-pin SOT
Features and Benefits
1. VCC
2. No connection
3. GND
NC
1 2
3
1 2 3
1. VCC
2. GND
3. GND
Package UA, 3-pin SIP
Chopper stabilization
null Low switchpoint drift over operating
temperature range
null Low stress sensitivity
Field-programmable for optimized
switchpoints
The A1184 device is a standard, two-wire, unipolar, Hall effect switches. The
operate point, B
OP
, can be field-programmed, after final packaging of the sensor
and placement into the application. This advanced feature allows the optimiza-
tion of the sensor switching performance, by effectively accounting for variations
caused by mounting tolerances for the device and the target magnet.
This family of 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 applica-
tion environments. Commonly found in a number of automotive applications, the
A1184 is 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 flows in either of two narrowly-specified ranges.
Any output current level outside of these two ranges is a fault condition. The
A1184 also features on-chip transient protection, and a Zener clamp to protect
against overvoltage conditions on the supply line.
The output current of the A1184 switches HIGH in the presence of a south polarity
magnetic field of sufficient strength; and switches LOW otherwise, including when
there is no significant magnetic field present.
Both devices are offered in two package styles: LH, a SOT-23W miniature low-
profile package for surface-mount applications, and UA, a three-lead ultramini
Single Inline Package (SIP) for through-hole mounting. Each package is available
in a lead (Pb) free version (suffix, –T) with 100% matte tin plated leadframe.
Factory-programmed versions are also available. Refer to: A1140, A1141, A1142,
A1143, A1145, and A1146.