3134
BIPOLAR HALL-EFFECT SWITCH
FOR HIGH-TEMPERATURE OPERATION
This low-hysteresis bipolar Hall-effect switch is an extremely
temperature-stable and stress-resistant sensor 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 stability by
compensating for temperature changes in the Hall element. Additionally,
internal compensation provides magnetic switch points that become more
sensitive with temperature, hence offsetting the usual degradation of the
magnetic field with temperature. Its low hysteresis makes this device
ideal for detecting small changes in magnetic field strength or for use
with inexpensive magnets.
The device includes on a single silicon chip a voltage regulator,
quadratic 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 volts 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 -40°C to +150°C. Three package styles provide a magneti-
cally optimized package for most applications. Suffix ‘–LT’ is a minia-
ture SOT-89/TO-243AA transistor package for surface-mount applica-
tions; suffix ‘–U’ is a three-lead plastic mini-SIP while suffix ‘–UA’ is a
three-lead ultra-mini-SIP.
Data Sheet
27631.4B*
V
X
CC
1
2
3
GROUND
Dwg. PH-003A
Pinning is shown viewed from branded side.
OUTPUT
SUPPLY
FEATURES
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
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
The A3134xU is last-time buy. Orders accepted
until April 15, 2002.
Always order by complete part number, e.g.,
A3134ELT
.
3134
LOW-HYSTERESIS
BIPOLAR HALL-EFFECT SWITCH
FOR HIGH-TEMP. 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
Output Rise Time
Output Fall Time
Symbol
V
CC
V
OUT(SAT)
I
OFF
I
CC
t
r
t
f
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)
R
L
= 820
Ω,
C
L
= 20 pF
R
L
= 820
Ω,
C
L
= 20 pF
Min.
3.8
175
0.05
3.2
5.0
100
100
Typ.
Max.
24
400
1.0
9.0
Units
V
mV
µA
mA
mA
ns
ns
MAGNETIC CHARACTERISTICS over operating supply voltage range.
Limits
Characteristic
Operate Point
Release Point
Hysteresis
Symbol
B
OP
B
RP
B
hys
Test Conditions
at T
A
= +25°C
Over Oper. Temp. Range
at T
A
= +25°C
Over Oper. Temp. Range
at T
A
= +25°C
Over Oper. Temp. Range
Min.
-40
-40
-50
-50
10
5.0
Typ.
8.5
—
-19
—
27
—
Max.
50
50
40
40
50
55
Units
G
G
G
G
G
G
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).
Typical values are at T
A
= +25°C and V
CC
= 12 V.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, 1999, Allegro MicroSystems, Inc.
3134
LOW-HYSTERESIS
BIPOLAR HALL-EFFECT SWITCH
FOR HIGH-TEMP. OPERATION
SENSOR LOCATIONS
(±0.005" [0.13 mm] die placement)
Suffix “LT”
ACTIVE AREA DEPTH
0.0305"
0.775 mm
NOM
0.090"
2.27 mm
0.050"
1.27 mm
APPLICATIONS INFORMATION
Hall effect applications information is available in the “Hall-Effect IC
Applications Guide” (AN 27701), which can be found in the latest issue of
Allegro MicroSystems Electronic Data Book,
AMS-702, or at
www.allegromicro.com
OPERATION
The output of these devices (pin 3) switches low when the magnetic field
at the Hall sensor exceeds the operate point threshold (B
OP
). At this point, the
output voltage is V
OUT(SAT)
. When the magnetic field is reduced to below the
release point (B
RP
) the device output goes high. Note especially that release
can occur when the magnetic field is removed but to ensure release, a field
reversal is required. The difference in the magnetic operate and release points
is called the hysteresis (B
hys
) of the device. This built-in hysteresis allows
clean switching of the output even in the presence of external mechanical
vibration and electrical noise.
A
1
2
3
Dwg. MH-008-4C
Suffix “U”
ACTIVE AREA DEPTH
0.0165"
0.42 mm
NOM
0.092"
2.33 mm
0.077"
1.96 mm
A
BRANDED
SURFACE
1
2
3
Dwg. MH-002-7C
Suffix “UA”
ACTIVE AREA DEPTH
0.0195"
0.50 mm
NOM
0.083"
2.10 mm
0.060"
1.51 mm
A
BRANDED
SURFACE
1
2
3
Dwg. MH-011-4C
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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