3121, 3122,
AND
Data Sheet
27621.4B
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE OPERATION
These Hall-effect switches are monolithic integrated circuits with
tighter magnetic specifications, designed to operate continuously over
extended temperatures to +150°C, and are more stable with both tem-
X
V
CC
1
32
perature and supply voltage changes. The unipolar switching characteristic makes these devices ideal for use with a simple bar or rod magnet.
The three basic devices (3121, 3122, and 3123) are identical except for
magnetic switch points.
Each device includes a voltage regulator for operation with supply
voltages of 4.5 voltas to 24 volts, reverse battery protection diode,
quadratic Hall-voltage generator, temperature compensation circuitry,
small-signal amplifier, Schmitt trigger, and an open-collector output to
sink up to 25 mA. With suitable output pull up, they can be used with
bipolar or CMOS logic circuits. The 3121 is an improved replacement
for the 3113 and 3119.
SUPPLY
Pinning is shown viewed from branded side.
ABSOLUTE MAXIMUM RATINGS
GROUND
Dwg. PH-003A
OUTPUT
at TA = +25°C
Supply Voltage, VCC...........................30 V
Reverse Battery Voltage, V
Magnetic Flux Density, B ....... Unlimited
Output OFF Voltage, V
Reverse Output Voltage, V
Continuous Output Current, I
Operating Temperature Range, T
Suffix ‘E–’ ................. -40°C to +85°C
Suffix ‘L–’ ............... -40°C to +150°C
Storage Temperature Range,
TS.............................. -65°C to +170°C
........ -30 V
RCC
................ 28 V
OUT
........ -0.5 V
OUT
... 25 mA
OUT
A
The first character of the part number suffix determines the device
operating temperature range. Suffix ‘E–’ is for the automotive and
industrial temperature range of -40°C to +85°C. Suffix ‘L–’ is for the
automotive and military temperature range of -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.
FEATURES and BENEFITS
■ Superior Temp. Stability for Automotive or Industrial Applications
■ 4.5 V to 24 V Operation … Needs Only An Unregulated Supply
■ Open-Collector 25 mA Output … Compatible with Digital Logic
■ Reverse Battery Protection
■ Activate with Small, Commercially Available Permanent Magnets
■ Solid-State Reliability … No Moving Parts
■ Small Size
■ Resistant to Physical Stress
Always order by complete part number, e.g., A3121EU .
3121, 3122,
AND
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
OPERATION
ELECTRICAL CHARACTERISTICS over operating temperature range, at V
= 12 V.
CC
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Supply Voltage V
Output Saturation Voltage V
OUT(SAT)
Output Leakage Current I
Supply Current I
Output Rise Time t
Output Fall Time t
CC
OFF
CC
r
f
Operating 4.5 — 24 V
I
= 20 mA, B > B
OUT
V
= 24 V, B < B
OUT
OP
RP
— 140 400 mV
— <1.0 10 µA
B < BRP (Output OFF) — 4.6 9.0 mA
RL = 820 Ω, CL = 20 pF — 0.04 2.0 µs
RL = 820 Ω, CL = 20 pF — 0.18 2.0 µs
MAGNETIC CHARACTERISTICS in gauss over operating supply voltage range.
Part Numbers*
A3121 A3122 A3123
Characteristic Min. Typ. Max. Min. Typ. Max. Min. Typ. Max
B
at TA = 25°C 250 350 450 280 340 400 250 345 440
OP
over operating temp. range 220 350 500 260 340 430 230 345 470
B
at TA = 25°C 125 245 380 140 235 330 180 240 300
RP
over operating temp. range 80 245 410 120 235 360 160 240 330
B
at TA = 25°C 70 105 140 70 105 140 70 105 140
hys
over operating temp. range 60 105 150 70 105 140 70 105 140
NOTES: Typical values are at TA = +25°C and VCC = 12 V.
B
= operate point (output turns ON); BRP = release point (output turns OFF); B
OP
*Complete part number includes a suffix to identify operating temperature range (E- or L-) and package type ( -LT, -U, or -UA).
FUNCTIONAL BLOCK DIAGRAM
1
V
CC
REG.
X
= hysteresis (BOP - BRP).
hys
3
OUTPUT
GROUND
2
Dwg. FH-005-2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1992, 1999, Allegro MicroSystems, Inc.
SWITCH POINTS OUTPUT SATURATION VOLTAGE
400
OPERATE POINT
300
200
100
SWITCH POINT IN GAUSS
TYPICAL OPERATING CHARACTERISTICS
RELEASE POINT
V = 12 V
CC
3121, 3122,
AND
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
OPERATION
I = 20 mA
OUT
V = 4.5–24 V
CC
0
-50
-25 25 75 125
0 50 100
AMBIENT TEMPERATURE IN °C
SUPPLY CURRENT
7.0
6.0
5.0
SUPPLY CURRENT IN mA
4.0
-50
-25
0 25 50 75
AMBIENT TEMPERATURE IN °C
B ≥ B
OP
B ≤ B
100
Dwg. GH-038
V = 12 V
CC
RP
125
Dwg. GH-039
150
-50
10
8.0
6.0
4.0
SUPPLY CURRENT IN mA
2.0
150
0
0
-25
0 25 50 75
AMBIENT TEMPERATURE IN °C
SUPPLY CURRENT
B ≥ B
OP
5
SUPPLY VOLTAGE IN VOLTS
10 15 20 25
100
B ≤ B
T = +25°C
150
125
Dwg. GH-040
RP
A
Dwg. GH-041
* Complete part number includes a suffix denoting operating temperature range (E- or L-) and package type ( -LT, -U, or -UA).
3121, 3122,
AND
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
OPERATION
SENSOR LOCATIONS
(±0.005" [0.13 mm] die placement)
Suffix “LT”
ACTIVE AREA DEPTH
0.030"
0.76 mm
NOM
0.089"
2.26 mm
A
1 32
Dwg. MH-008-2C
Suffix “U”
ACTIVE AREA DEPTH
0.016"
0.41 mm
NOM
0.091"
2.31 mm
0.070"
1.78 mm
0.043"
1.09 mm
OPERATION
The output of these devices (pin 3) switches low when the magnetic field at the Hall sensor exceeds the operate point threshold (B
At this point, the output voltage is V
OUT(SAT)
. When the magnetic field
OP
).
is reduced to below the release point threshold (BRP), the device output
goes high. The difference in the magnetic operate and release points is
called the hysteresis (B
) of the device. This built-in hysteresis allows
hys
clean switching of the output even in the presence of external mechanical vibration and electrical noise.
APPLICATIONS INFORMATION
Hall effect applications information is available in the “Hall-Effect
IC Applications Guide”, which can be found in the latest issue of
Allegro MicroSystems Data Book AMS-702.
CHANGE IN OPERATE POINT
20
15
T = +25°C
A
BRANDED
SURFACE
ACTIVE AREA DEPTH
0.019"
0.48 mm
NOM
BRANDED
SURFACE
A
1 32
Suffix “UA”
0.082"
2.07 mm
A
1 32
Dwg. MH-002-2B
0.055"
1.38 mm
Dwg. MH-011-2C
10
5.0
0
CHANGE IN OPERATE POINT IN GAUSS
-5.0
0
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
5
SUPPLY VOLTAGE IN VOLTS
10 15 20 25
Dwg. GH-042
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
PACKAGE DESIGNATOR ‘LT’
Dimensions in Inches
(for reference only)
3121, 3122,
OPERATION
AND
3123
0.155
0.167
0.035
0.047
0.059
BSC
0.173
0.181
0.064
0.072
0.090
1
23
0.118
BSC
0.102
0.014
0.019
0.017
0.022
Dimensions in Millimeters
(controlling dimensions)
4.40
4.60
1.62
1.83
0.055
0.063
0.014
0.017
0.084
0.090
Dwg. MA-009-3 in
1.40
1.60
0.35
0.44
3.94
4.25
0.89
1.20
1.50
BSC
NOTE: Exact body and lead configuration at vendor's option within limits shown.
1
23
3.00
BSC
2.29
2.60
0.36
0.48
0.44
0.56
2.13
2.29
Dwg. MA-009-3 mm
3121, 3122,
AND
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
OPERATION
PACKAGE DESIGNATOR ‘U’
Dimensions in Inches Dimensions in Millimeters
(controlling dimensions) (for reference only)
SEE NOTE
0.181
0.176
0.600
0.560
0.086
MAX
0.183
0.178
1 2 3
0.050
0.100
0.063
0.059
0.016
45°
0.018
0.015
Dwg. MH-003D in
SEE NOTE
4.60
4.47
15.24
14.23
2.18
MAX
4.65
4.52
1 2 3
1.27
2.54
1.60
1.50
45°
0.46
0.38
0.41
Dwg. MH-003D 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.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3121, 3122,
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
OPERATION
PACKAGE DESIGNATOR ‘UA’
Dimensions in Inches Dimensions in Millimeters
(controlling dimensions) (for reference only)
AND
3123
SEE NOTE
45°
0.122
0.117
0.640
0.600
0.085
123
MAX
0.164
0.159
0.050
BSC
0.062
0.058
0.031
0.016
0.015
Dwg. MH-014D in
45°
SEE NOTE
45°
3.10
2.97
16.26
15.24
2.16
123
MAX
4.17
4.04
1.27
BSC
1.57
1.47
45°
0.79
0.38
0.41
Dwg. MH-014D mm
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.
3121, 3122,
AND
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE
OPERATION
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 patents
pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to
time, such departures from the detail specifications as may be required
to permit improvements in the performance, reliability, or
manufacturability of its products. Before placing an order, the user is
cautioned to verify that the information being relied upon is current.
Allegro products are not authorized for use as critical components
in life-support appliances, devices, or systems without express written
approval.
The information included herein is believed to be accurate and
reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of
third parties that may result from its use.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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