A1185 and A1186

A1185-DS, Rev. 1

Worcester, Massachusetts 01615-0036 (508) 853-5000

115 Northeast Cutoff, Box 15036

www.allegromicro.com

Allegro MicroSystems, Inc.

ABSOLUTE MAXIMUM RATINGS

Magnetic Flux Density, B .........................Unlimited

Operating Temperature

On-chip protection

Supply transient protection

Reverse-battery protection

On-board voltage regulator

3.5 V to 24 V operation

Ultrasensitive 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

Low switchpoint drift over operating

temperature range

Low stress sensitivity

Field-programmable for optimized

switchpoints

The A1185 and A1186 are ultrasensitive, two-wire, unipolar Hall effect switches.

sor 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 new DABIC5

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 A1185 and A1186 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 flows in either of two narrowly-specified ranges.

level outside of these two ranges is a fault condition.

Other features of the A1185 and A1186 devices include on-chip transient protec-

tion and a Zener clamp on the power supply to protect against overvoltage condi-

tions on the supply line.

there is no significant magnetic field present. The A1185 has an inverted output

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: A1145 and A1146.