HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE OPERATION
These Hall-effect latches are extremely temperature-stable and stress-
resistant sensors especially suited for operation over extended temperature
ranges to +150
C. Superior high-temperature performance is made possible
through a novel Schmitt trigger circuit that maintains operate and release
point symmetry by compensating for temperature changes in the Hall ele-
ment. Additionally, internal compensation provides magnetic switch points
that become more sensitive with temperature, hence offsetting the usual
degradation of the magnetic field with temperature. The symmetry capability
makes these devices ideal for use in pulse-counting applications where duty
cycle is an important parameter. The four basic devices (3185, 3187, 3188,
and 3189) are identical except for magnetic switch points.
Each device includes on a single silicon chip a voltage regulator, qua-
dratic Hall-voltage generator, temperature compensation circuit, signal
amplifier, Schmitt trigger, and a buffered open-collector output to sink up to
25 mA. The on-board regulator permits operation with supply voltages of 3.8
to 24 volts.
The first character of the part number suffix determines the device
operating temperature range. Suffix `E' is for -40
C to +85
C, and suffix
`L' is for -40
C to +150
C. Three package styles provide a magnetically
optimized package for most applications. Suffix `LT' is a miniature SOT89/
TO-243AA transistor package for surface-mount applications; suffix `UA' is
a three-lead ultra-mini-SIP.
Data Sheet
27609.2B*
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
C
Supply Voltage, V
CC
............................ 30 V
Reverse Battery Voltage, V
RCC
........... -30 V
Magnetic Flux Density, B ........... Unlimited
Output OFF Voltage, V
OUT
.................. 30 V
Reverse Output Voltage, V
OUT
.......... -0.5 V
Continuous Output Current, I
OUT
..... 25 mA
Operating Temperature Range, T
A
Suffix `E' ................... -40
C to +85
C
Suffix `L' ................. -40
C to +150
C
Storage Temperature Range,
T
S
............................... -65
C to +170
C
FEATURES
s Symmetrical Switch Points
s Superior Temperature Stability
s Operation From Unregulated Supply
s Open-Collector 25 mA Output
s Reverse Battery Protection
s Activate With Small, Commercially Available Permanent Magnets
s Solid-State Reliability
s Small Size
s Resistant to Physical Stress
Pinning is shown viewed from branded side.
Always order by complete part number: the prefix `A' + the basic four-digit
part number + a suffix to indicate operating temperature range +
a suffix to indicate package style, e.g., A3185ELT .
3185
THRU
3189
Dwg. PH-003A
1
SUPPLY
V
CC
GROUND
3
2
OUTPUT
X
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ELECTRICAL CHARACTERISTICS over operating temperature range, at V
CC
= 12 V.
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Supply Voltage
V
CC
Operating
3.8
--
24
V
Output Saturation Voltage
V
OUT(SAT)
I
OUT
= 20 mA, B > B
OP
--
175
400
mV
Output Leakage Current
I
OFF
V
OUT
= 24 V, B < B
RP
--
0.05
5.0
A
Supply Current
I
CC
B < B
RP
(Output OFF)
--
4.75
8.0
mA
B > B
OP
(Output ON)
--
5.7
--
mA
Output Rise Time
t
r
R
L
= 820
, C
L
= 20 pF
--
100
--
ns
Output Fall Time
t
f
R
L
= 820
, C
L
= 20 pF
--
100
--
ns
MAGNETIC CHARACTERISTICS in gauss over operating supply voltage range.
Part Numbers*
A3185
A3187
A3188
A3189
Characteristic
Min.
Max.
Min.
Max.
Min.
Max.
Min.
Max.
B
OP
at T
A
= 25
C
170
270
50
150
100
180
50
230
over operating temp. range
140
300
50
175
80
200
50
250
B
RP
at T
A
= 25
C
-270
-170
-150
-50
-180
-100
-230
-50
over operating temp. range
-300
-140
-175
-50
-200
-80
-250
-50
B
hys
at T
A
= 25
C
340
540
100
300
200
360
100
460
over operating temp. range
280
600
100
350
160
400
100
500
FUNCTIONAL BLOCK DIAGRAM
NOTES: B
OP
= operate point (output turns ON); B
RP
= release point (output turns OFF); B
hys
= hysteresis (B
OP
- B
RP
).
As used here, negative flux densities are defined as less than zero (algebraic convention).
*Complete part number includes a suffix to identify operating temperature range (E or L) and package type ( LT or UA).
V
CC
X
REG.
Dwg. FH-005-3
GROUND
OUTPUT
1
3
2
Copyright 1995, 2002 Allegro MicroSystems, Inc.
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
www.allegromicro.com
TYPICAL OPERATING CHARACTERISTICS
A3185* SWITCH POINTS
A3187* SWITCH POINTS
* Complete part number includes a suffix denoting operating temperature range (E or L) and package type (LT or UA).
OUTPUT SATURATION VOLTAGE
SUPPLY CURRENT
SUPPLY CURRENT
OPERATE POINT
0
50
100
AMBIENT TEMPERATURE IN
C
-50
Dwg. GH-027
SWITCH POINT IN GAUSS
0
50
100
-50
-100
OPERATE POINT
RELEASE POINT
V = 12 V
CC
150
150
-150
-25
25
75
125
0
25
50
75
100
AMBIENT TEMPERATURE IN
C
-50
Dwg. GH-028
125
-25
V = 12 V
CC
B
B
RP
SUPPLY CURRENT IN mA
7.0
6.0
5.0
4.0
B
B
OP
150
0
25
50
75
100
300
0
AMBIENT TEMPERATURE IN
C
200
100
-50
Dwg. GH-029
SATURATION VOLTAGE IN mV
150
-25
125
I = 20 mA
V = 4.524 V
OUT
CC
10
15
20
25
SUPPLY VOLTAGE IN VOLTS
0
Dwg. GH-037
5
CHANGE IN OPERATE POINT IN GAUSS
-5.0
0
5.0
10
15
20
T = +25
C
A
0
50
100
AMBIENT TEMPERATURE IN
C
-50
Dwg. GH-026
SWITCH POINT IN GAUSS
0
100
200
-100
-200
OPERATE POINT
RELEASE POINT
V = 12 V
CC
150
300
-300
-25
25
75
125
10
15
20
25
SUPPLY VOLTAGE IN VOLTS
0
Dwg. GH-030
5
SUPPLY CURRENT IN mA
0
2.0
4.0
6.0
8.0
10
B
B
OP
B
B
RP
T = +25
C
A
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
SENSOR LOCATIONS
(
0.005" [0.13 mm] die placement)
Allegro
Package Designators "LT"
1
3
2
Dwg. MH-008-4C
0.0305"
0.775 mm
NOM
ACTIVE AREA DEPTH
0.050"
1.27 mm
0.090"
2.27 mm
A
Package Designators "UA"
1
3
2
Dwg. MH-011-4C
0.0195"
0.50 mm
NOM
BRANDED
SURFACE
ACTIVE AREA DEPTH
0.083"
2.10 mm
0.060"
1.51 mm
A
The simplest form of magnet that will operate these devices is a ring
magnet, as shown below. Other methods of operation are possible.
Dwg. A-11,899
OPERATION
In operation, the output transistor is OFF until the strength of the mag-
netic field perpendicular to the surface of the chip exceeds the threshold or
operate point (B
OP
). When the field strength exceeds B
OP
, the output transis-
tor switches ON and is capable of sinking 25 mA of current.
The output transistor switches OFF when magnetic field reversal results
in a magnetic flux density below the OFF threshold (B
RP
). This is illustrated
in the transfer characteristics graph (A3187* shown).
Note that the device latches; that is, a south pole of sufficient strength
will turn the device ON. Removal of the south pole will leave the device ON.
The presence of a north pole of sufficient strength is required to turn the
device OFF. Powering up in the absence of a magnetic field (less than B
OP
and higher than B
RP
) will allow an indeterminate output state. The correct
state is warranted after the first excursion beyond B
OP
or B
RP
.
APPLICATIONS INFORMATION
Extensive applications information on magnets and Hall-effect sensors is
also available in the Allegro Integrated and Discrete Semiconductors Data
Book or Application Note 27701.
30 V
MAX
0
+B
0
OUTPUT VOLTAGE IN VOLTS
FLUX DENSITY
Dwg. GH-034-4
-B
RP
B
V
OUT(SAT)
BB
V
OP
B
Although sensor location is accurate to three
sigma for a particular design, product improve-
ments may result in small changes to sensor
location.
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
www.allegromicro.com
Dwg. MA-009-3A in
1
2
3
0.072
0.064
0.167
0.155
0.059
BSC
0.0189
0.0142
0.047
0.035
0.102
0.090
0.063
0.055
0.0173
0.0138
0.090
0.084
0.0221
0.0173
0.118
BSC
0.181
0.173
Dwg. MA-009-3A mm
1
2
3
4.60
4.40
1.83
1.62
4.25
3.94
1.50
BSC
0.48
0.36
1.20
0.89
2.60
2.29
1.60
1.40
0.44
0.35
2.29
2.13
0.56
0.44
3.00
BSC
PACKAGE DESIGNATOR `LT'
(SOT89/TO-243AA)
Dimensions in Inches
(for reference only)
Dimensions in Millimeters
(controlling dimensions)
NOTES: 1.
Exact body and lead configuration at vendor's option within limits shown.
2.
Supplied in bulk pack (500 pieces per bag) or add "TR" to part number for tape and reel.
3.
Only low-temperature (
240
C) reflow-soldering techniques are recommended for SOT89 devices.
1
B
0.098
0.031
0.102
0.047
0.181
0.079
Dwg. MA-012-3 in
Pads 1, 2, 3, and A -- Standard SOT89 Layout
Pads 1, 2, 3, and B -- Low-Stress Version
Pads 1, 2, and 3 only -- Lowest Stress, But Not Self Aligning
2
0.028
TYP
0.031
TYP
A
3
1
3
B
2.5
0.8
2.6
1.2
4.6
2.0
Dwg. MA-012-3 mm
Pads 1, 2, 3, and A -- Standard SOT89 Layout
Pads 1, 2, 3, and B -- Low-Stress Version
Pads 1, 2, and 3 only -- Lowest Stress, But Not Self Aligning
2
0.7
TYP
0.8
TYP
A
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