A1185_06 ALLEGRO [Allegro MicroSystems], A1185_06 Datasheet

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A1185_06

Manufacturer Part Number
A1185_06
Description
Ultrasensitive Two-Wire Field-Programmable Chopper-Stabilized Unipolar Hall-Effect Switches
Manufacturer
ALLEGRO [Allegro MicroSystems]
Datasheet
Features and Benefits
▪ Chopper stabilization
▪ Field programmable for optimized switchpoints
▪ On-chip protection
Packages: 3 pin SOT23W (suffix LH), and
3 pin SIP (suffix UA)
Not to scale
A1185-DS, Rev. 2
▫ Low switchpoint drift over operating
▫ Low sensitivity to stress
▫ Reverse-battery protection
▫ On-board voltage regulator
▫ 3.5 to 24 V operation
▫ Supply transient protection
temperature range
V+
0.01 uF
VCC
Chopper-Stabilized Unipolar Hall-Effect Switches
Ultrasensitive Two-Wire Field-Programmable
Functional Block Diagram
Clock/Logic
Amp
Program/Lock
Programming
Logic
Low-Pass
Filter
Description
The A1185 and A1186 are ultrasensitive, two-wire, unipolar
Hall effect switches. The operate point, B
programmed, after final packaging of the sensor and
placement into the application. This advanced feature allows
the optimization 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 application 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 applications, because they require one less
wire than the more traditional open-collector output switches.
Continued on the next page…
Offset
Adjust
Regulator
Package UA Only
To all
subcircuits
GND
A1185 and A1186
GND
OP
, can be field-

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A1185_06 Summary of contents

Page 1

Ultrasensitive Two-Wire Field-Programmable Chopper-Stabilized Unipolar Hall-Effect Switches Features and Benefits ▪ Chopper stabilization ▫ Low switchpoint drift over operating temperature range ▫ Low sensitivity to stress ▪ Field programmable for optimized switchpoints ▪ On-chip protection ▫ Supply transient protection ▫ ...

Page 2

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches Description (continued) Additionally, the system designer gains inherent diagnostics because output current normally flows in either of two narrowly- specified ranges. This provides distinct current ranges for I and I . Any ...

Page 3

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches ELECTRICAL CHARACTERISTICS Characteristic Symbol Supply Voltage 1 Supply Current 2 Supply Zener Clamp Voltage V 3 Supply Zener Clamp Current I Reverse Supply Current 4 Output Slew Rate Chopping Frequency 5 Power-On ...

Page 4

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches I versus Ambient Temperature CC(L) at Various Levels of V (A1185 and A1186 - 100 Ambient Temperature Set by Specific Programming Bit ...

Page 5

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Package Thermal Resistance *Additional thermal information available on Allegro Web site. Ultrasensitive Two-Wire Field-Programmable Symbol Test Conditions* Package LH, 1-layer ...

Page 6

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches Operation The output the A1185 switches low after the magnetic CC field at the Hall sensor exceeds the operate point threshold, B When the magnetic field is reduced to ...

Page 7

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches Chopper Stabilization Technique A limiting factor for switchpoint accuracy when using Hall effect technology is the small signal voltage developed across the Hall element. This voltage is proportionally small relative to the ...

Page 8

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches For additional general application information, visit the Allegro Web site at www. allegromicro.com. Typical Application and Programming Circuit The A118x family of devices MUST be protected by an exter- nal bypass capacitor, ...

Page 9

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches Power Derating The device must be operated below the maximum junction temperature of the device Under certain combinations of J(max) peak conditions, reliable operation may require derating sup- plied power ...

Page 10

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches Programming Protocol The operate switchpoint can be field-programmed so, a coded series of voltage pulses through the VCC pin is used to set bitfields in onboard registers. ...

Page 11

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches The pulse sequences consist of the following groups of pulses enable sequence bitfield address sequence. 3. When permanently setting the bitfield, a long V ing pulse. (Note: Blown ...

Page 12

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches The first segment of code is a Enabling Addressing Mode. keying sequence used to enable the bitfield addressing mode. As shown in figure 7, this segment consists of one short V one ...

Page 13

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches Preliminary dimensions, for reference only Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only (reference JEDEC TO-236 AB, except case width and terminal tip-to-tip) Dimensions exclusive of mold flash, ...

Page 14

A1185 and A1186 Chopper-Stabilized Unipolar Hall Effect Switches .122 .117 The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other ...

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