3185
THRU
3189
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 SOT-
89/TO-243AA transistor package for surface-mount applications; suffix ‘–U’
is a three-lead plastic mini-SIP, while suffix ‘–UA’ is a three-lead ultra-mini-
SIP.
Data Sheet
27609.2A*
V
X
CC
1
2
3
GROUND
Dwg. PH-003A
OUTPUT
SUPPLY
Pinning is shown viewed from branded side.
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
The A3185xU, A3188xU, and A3189xU are discontinued
and shown for reference only.
The A3187xU is last-time buy; orders accepted only
until October 28, 2002
FEATURES
s
s
s
s
s
s
s
s
s
Symmetrical Switch Points
Superior Temperature Stability
Operation From Unregulated Supply
Open-Collector 25 mA Output
Reverse Battery Protection
Activate With Small, Commercially Available Permanent Magnets
Solid-State Reliability
Small Size
Resistant to Physical Stress
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
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
FUNCTIONAL BLOCK DIAGRAM
1
V
CC
REG.
X
3
OUTPUT
GROUND
2
Dwg. FH-005-3
ELECTRICAL CHARACTERISTICS over operating temperature range, at V
CC
= 12 V.
Limits
Characteristic
Supply Voltage
Output Saturation Voltage
Output Leakage Current
Supply Current
Symbol
V
CC
V
OUT(SAT)
I
OFF
I
CC
Test Conditions
Operating
I
OUT
= 20 mA, B > B
OP
V
OUT
= 24 V, B < B
RP
B < B
RP
(Output OFF)
B > B
OP
(Output ON)
Output Rise Time
Output Fall Time
t
r
t
f
R
L
= 820
Ω,
C
L
= 20 pF
R
L
= 820
Ω,
C
L
= 20 pF
Min.
3.8
—
—
—
—
—
—
Typ.
—
175
0.05
4.75
5.7
100
100
Max.
24
400
5.0
8.0
—
—
—
Units
V
mV
µA
mA
mA
ns
ns
MAGNETIC CHARACTERISTICS in gauss over operating supply voltage range.
Part Numbers*
A3185
Characteristic
B
OP
at T
A
= 25°C
over operating temp. range
B
RP
at T
A
= 25°C
over operating temp. range
B
hys
at T
A
= 25°C
over operating temp. range
Min.
170
140
-270
-300
340
280
Max.
270
300
-170
-140
540
600
A3187
Min.
50
50
-150
-175
100
100
Max.
150
175
-50
-50
300
350
A3188
Min.
100
80
-180
-200
200
160
Max.
180
200
-100
-80
360
400
A3189
Min.
50
50
-230
-250
100
100
Max.
230
250
-50
-50
460
500
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, U, or UA).
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, 2002 Allegro MicroSystems, Inc.
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
TYPICAL OPERATING CHARACTERISTICS
A3185* SWITCH POINTS
300
150
A3187* SWITCH POINTS
200
OPERATE POINT
100
OPERATE POINT
SWITCH POINT IN GAUSS
100
SWITCH POINT IN GAUSS
50
0
V
CC
= 12 V
0
V
CC
= 12 V
-100
-50
RELEASE POINT
-100
RELEASE POINT
-200
-300
-50
-25
0
25
50
75
100
125
150
Dwg. GH-026
-150
-50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN
°
C
AMBIENT TEMPERATURE IN
°
C
Dwg. GH-027
OUTPUT SATURATION VOLTAGE
300
SUPPLY CURRENT
7.0
I
OUT
= 20 mA
V
CC
= 4.5–24 V
V
CC
= 12 V
SATURATION VOLTAGE IN mV
SUPPLY CURRENT IN mA
200
6.0
B
≥
B
OP
100
5.0
B
≤
B
RP
0
-50
-25
0
25
50
75
100
125
150
4.0
-50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN
°
C
Dwg. GH-029
AMBIENT TEMPERATURE IN
°
C
Dwg. GH-028
SUPPLY CURRENT
10
OPERATE POINT
20
8.0
CHANGE IN OPERATE POINT IN GAUSS
15
T
A
= +25°C
10
SUPPLY CURRENT IN mA
6.0
B
≥
B
OP
B
≤
B
RP
4.0
5.0
2.0
T
A
= +25°C
0
0
0
5
10
15
20
25
Dwg. GH-030
-5.0
0
5
10
15
20
25
Dwg. GH-037
SUPPLY VOLTAGE IN VOLTS
SUPPLY VOLTAGE IN VOLTS
* Complete part number includes a suffix denoting operating temperature range (E or L) and package type (LT, U, or UA).
www.allegromicro.com
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
SENSOR LOCATIONS
(±0.005” [0.13 mm] die placement)
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
.
Package Designators “LT”
ACTIVE AREA DEPTH
0.0305"
0.775 mm
NOM
0.090"
2.27 mm
0.050"
1.27 mm
A
1
2
3
Dwg. MH-008-4C
Package Designator “U”
0.092"
2.33 mm
0.077"
1.96 mm
OUTPUT VOLTAGE IN VOLTS
ACTIVE AREA DEPTH
0.0165"
0.42 mm
NOM
30 V
MAX
V
BB
B
RP
B
OP
A
BRANDED
SURFACE
1
2
3
V
OUT(SAT)
0
-B
Dwg. MH-002-7C
0
FLUX DENSITY
+B
Dwg. GH-034-4
Package Designators “UA” and "UA-TL"
ACTIVE AREA DEPTH
0.0195"
0.50 mm
NOM
0.083"
2.10 mm
The simplest form of magnet that will operate these devices is a ring
magnet, as shown below. Other methods of operation are possible.
0.060"
1.51 mm
Allegro
A
BRANDED
SURFACE
1
2
3
Dwg. A-11,899
Dwg. MH-011-4C
Although sensor location is accurate to three
sigma for a particular design, product improve-
ments may result in small changes to sensor
location.
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.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3185
THRU
3189
HALL-EFFECT LATCHES
FOR HIGH-TEMPERATURE
OPERATION
PACKAGE DESIGNATOR ‘U’
Dimensions in Inches
(controlling dimensions)
Dimensions in Millimeters
(for reference only)
0.183
0.178
0.063
0.059
4.65
4.52
1.60
1.50
0.181
0.176
45°
0.086
MAX
4.60
4.47
45°
2.18
MAX
1
2
3
0.018
1
2
3
0.46
0.600
0.560
0.0189
0.0142
SEE NOTE
0.0173
0.0138
15.24
14.23
0.48
0.36
SEE NOTE
0.44
0.35
0.050
0.100
Dwg. MH-003E in
1.27
2.54
Dwg. MH-003E mm
Devices in the ‘U’ package are
not recommended for new design
NOTES: 1. Tolerances on package height and width represent allowable mold offsets. Dimensions given are
measured at the widest point (parting line).
2. Exact body and lead configuration at vendor’s option within limits shown.
3. Height does not include mold gate flash.
4. Recommended minimum PWB hole diameter to clear transition area is 0.035" (0.89 mm).
5. Where no tolerance is specified, dimension is nominal.
6. Minimum lead length was 0.500" (12.70 mm). If existing product to the original specifications is not acceptable,
contact sales office before ordering.
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