Page 1
The A3240-- 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 dynamic offset cancellation, which reduces the
residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress.
The device includes on a single silicon chip a voltage regulator,
Hall-voltage generator, small-signal amplifier, chopper stabilization,
Schmitt trigger, and a short-circuit protected open-collector output to
sink up to 25 mA. A south pole of sufficient strength will turn the output
ON. An on-board regulator permits operation with supply voltages of
4.2 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
‘L–’ is -40°C to +150°C. Three package styles provide a magnetically
optimized package for most applications. Suffix ‘–LH’ is a modified
SOT-23 surface-mount package, ‘–LT’ is a miniature SOT-89/TO243AA transistor package for surface-mount applications; while suffix
‘–UA’ is a three-lead ultra-mini-SIP for through-hole mounting.
Data Sheet
27621.20
FEATURES
■ Resistant to Physical Stress
■ Superior Temperature Stability
■ Output Short-Circuit Protection
■ Operation From Unregulated Supply
■ Reverse Battery Protection
■ Solid-State Reliability
■ Small Size
Suffix ‘–LT’ & ‘–UA’ Pinning
Pinning is shown viewed from branded side.
CHOPPER-STABILIZED, PRECISION
HALL-EFFECT SWITCH
3240
Supply Voltage, VCC........................ 26.5 V
Reverse Battery Voltage, V
RCC
.......... -30 V
Magnetic Flux Density, B ........... Unlimited
Output OFF Voltage, V
OUT
................. 26 V
Continuous Output Current,
I
OUT
....................... Internally Limited
Reverse Output Current, I
OUT
........ -50 mA
Package Power Dissipation, PD. See Graph
Junction Temperature, TJ............... +170°C
Operating Temperature Range, T
A
Suffix ‘E–’ .................. -40°C to +85°C
Suffix ‘L–’ ................ -40°C to +150°C
Storage Temperature Range,
TS.............................. -65°C to +170°C
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Always order by complete part number: the prefix ‘A’ + the basic fourdigit part number + a suffix to indicate operating temperature range +
a suffix to indicate package style, e.g., A3240ELH .
Dwg. PH-003-2
1
SUPPLY
V
CC
GROUND
32
OUTPUT
X
PTCT
Page 2
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
2
FUNCTIONAL BLOCK DIAGRAM
Copyright © 2000 Allegro MicroSystems, Inc.
Suffix ‘–LH’ Pinning
Dwg. FH-020-1
GROUND
OUTPUT
<1Ω
X
DYNAMIC
OFFSET CANCELLATION
SUPPLY
CONTROL
CURRENT
LIMIT
REG.
SAMPLE
& HOLD
LOW-PASS
FILTER
TO ALL
SUBCIRCUITS
600
400
200
20 60 100 140
0
AMBIENT TEMPERATURE in °C
ALLOWABLE PACKAGE POWER DISSIPATION in MILLIWATTS
Dwg. GH-046-2C
Suffix "–UA"
R
θJA
= 206°C/W
40 80 120 180
700
500
300
100
160
Suffix "–LT"
R
θJA
= 258°C/W
Suffix "–LH"
R
θJA
= 248°C/W
Suffix "E–"
Suffix "L–"
Dwg. PH-003-4
SUPPLY
GROUND
OUTPUT
V
CC
X
PTCT
12
3
Page 3
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
www.allegromicro.com
3
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Supply Voltage Range V
CC
Operating, TJ < 170°C
1
4.2 – 24 V
Output Leakage Current I
OFF
V
OUT
= 24 V, B < B
RP
– – 10 µA
Output Saturation Voltage V
OUT(SAT)
I
OUT
= 20 mA, B > B
OP
– 185 500 mV
Output Current Limit I
OM
B > B
OP
30 – 60 mA
Power-On Time t
po
VCC > 4.2 V – – 50 µs
Chopping Frequency f
C
– 340 – kHz
Output Rise Time t
r
RL = 820 Ω, CL = 20 pF – 0.2 2.0 µs
Output Fall Time t
f
RL = 820 Ω, CL = 20 pF – 0.1 2.0 µs
Supply Current I
CC
B < BRP, VCC = 12 V – 3.0 6.0 mA
B > BOP, VCC = 12 V – 4.0 6.0 mA
Reverse Battery Current I
CC
V
RCC
= -30 V – – -5.0 mA
Zener Voltage VZ + V
D
ICC = 15 mA, TA = 25°C 283237 V
Zener Impedance zz + z
D
ICC = 15 mA, TA = 25°C–50–Ω
NOTES:1. Maximum voltage must be adjusted for power dissipation and junction temperature.
2. BOP = operate point (output turns on); BRP = release point (output turns off).
3. Typical Data is at TA = +25°C and VCC = 12 V and is for design information only.
ELECTRICAL CHARACTERISTICS over operating temperature range.
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Operate Point B
OP
– 35 50 G
Release Point B
RP
5.0 25 – G
Hysteresis B
hys
BOP - B
RP
– 10 – G
NOTE: Typical Data is at TA = +25°C and VCC = 12 V and is for design information only.
MAGNETIC CHARACTERISTICS over operating supply voltage and temperature ranges.
Page 4
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
4
TYPICAL OPERATING CHARACTERISTICS
as a function of temperature
SUPPLY CURRENT
OUTPUT SATURATION VOLTAGE
SWITCH POINTS
0 50 100
AMBIENT TEMPERATURE IN °C
-50
Dwg. GH-026-5
SWITCH POINTS IN GAUSS
30
OPERATE POINT
150-25 25 75 125
40
50
0
10
20
VCC = 4.5 V
V
CC
= 24 V
RELEASE POINT
0 25 50 75 100
300
0
AMBIENT TEMPERATURE IN °C
200
100
-50
Dwg. GH-029-4
SATURATION VOLTAGE IN mV
150-25 125
IOUT = 20 mA
V
CC = 12 V
6.0
SUPPLY CURRENT IN mA
5.0
4.0
3.0
2.0
0 255075100
AMBIENT TEMPERATURE IN °C
-50
Dwg. GH-028-5
125-25 150
OUTPUT ON, B > B
OP
OUTPUT OFF, B < B
RP
VCC = 12 V
Page 5
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
www.allegromicro.com
5
SUPPLY CURRENT
OUTPUT SATURATION VOLTAGE
TYPICAL OPERATING CHARACTERISTICS
as a function of supply voltage
SWITCH POINTS
4.0 4.5 5.0
SUPPLY VOLTAGE IN VOLTS
3.0
Dwg. GH-021-2
3.5
RELEASE POINT
SWITCH POINT IN GAUSS
40
30
20
10
0
OPERATE POINT
24
TA = 150°C
T
A
= -40°C
4.0 4.5 5.0
SUPPLY VOLTAGE IN VOLTS
3.0
Dwg. GH-055-1
3.5
24
TA = 150°C
T
A = +25°C
T
A = -40°C
IOUT = 20 mA
250
150
SATURATION VOLTAGE IN mV
200
225
175
4.0 6.0 9.0
SUPPLY VOLTAGE IN VOLTS
3.0
Dwg. GH-058-4
5.0 12
TA = 150°C
T
A
= +25°C
T
A
= -40°C
7.0
5.0
3.0
1.0
SUPPLY CURRENT IN mA
6.0
4.0
2.0
8.0
0
OUTPUT ON
10 118.07.0
Page 6
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
6
SENSOR LOCATIONS
(±0.005" [0.13 mm] die placement)
Package Designator ‘LH’
Package Designators ‘UA’ and ‘UA-TL’
Although sensor location is accurate to three sigma for a
particular design, product improvements may result in small
changes to sensor location.
Package Designator ‘LT’
0.038"
0.96 mm
1 2
Dwg. MH-025
0.011"
0.28 mm
NOM
ACTIVE AREA DEPTH
0.059"
1.49 mm
A
3
0.045"
1.14 mm
1 32
Dwg. MH-008-8
0.030"
0.76 mm
NOM
ACTIVE AREA DEPTH
0.088"
2.24 mm
A
1 32
Dwg. MH-011-9A
0.018"
0.46 mm
NOM
BRANDED
SURFACE
ACTIVE AREA DEPTH
0.080"
2.04 mm
0.056"
1.44 mm
A
Allegro
Page 7
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
www.allegromicro.com
7
CRITERIA FOR DEVICE QUALIFICATION
Qualification Test Test Method and Test Conditions Test Length Samples Comments
Biased Humidity (HAST) TA = 130°C, RH = 85% 50 hrs 77 VCC = V
OUT
= 5 V
High-Temperature JESD22-A108, 408 hrs 77 VCC = 24 V,
Operating Life (HTOL) TA = 150°C, TJ ≤ 170°CV
OUT
= 20 V
Accelerated HTOL TA = 175°C, TJ = 190°C 504 hrs 77 VCC = 24 V,
V
OUT
= 20 V
Autoclave, Unbiased JESD22-A102, Condition C, 96 hrs 77
TA = 121°C, 15 psig
High-Temperature MIL-STD-883, Method 1008, 1000 hrs 77
(Bake) Storage Life TA = 170°C
Temperature Cycle MIL-STD-883, Method 1010, 500 cycles 77
-65°C to +150°C
Latch-Up — Pre/Post 6
Reading
Electro-Thermally — Pre/Post 6
Induced Gate Leakage Reading
ESD, CDF-AEC-Q100-002 Pre/Post 3 per Test to failure,
Human Body Model Reading test All leads > 1500 V
ESD, JESD22-A115 Pre/Post 3 per Test to failure,
Macine Model Reading test All leads > 200 V
Electrical Distributions Per Specification — 30
All Allegro sensors are subjected to stringent qualification requirements prior to being released to production.
To become qualified, except for the destructive ESD tests, no failures are permitted.
Page 8
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
8
FUNCTIONAL DESCRIPTION
Chopper-Stabilized Technique. The Hall element can be
considered as a resistor array similar to a Wheatstone bridge. A
large portion of the offset is a result of the mismatching of these
resistors. These devices use a proprietary dynamic offset
cancellation technique, with an internal high-frequency clock to
reduce the residual offset voltage of the Hall element that is
normally caused by device overmolding, temperature dependencies, and thermal stress. The chopper-stabilizing technique
cancels the mismatching of the resistor circuit by changing the
direction of the current flowing through the Hall plate using
CMOS switches and Hall voltage measurement taps, while
maintaing the Hall-voltage signal that is induced by the external
magnetic flux. The signal is then captured by a sample-andhold circuit and further processed using low-offset bipolar
circuitry. This technique produces devices that have an
extremely stable quiescent Hall output voltage, are immune to
thermal stress, and have precise recoverability after temperature
cycling. This technique will also slightly degrade the device
output repeatability. A relatively high sampling frequency is
used in order that faster signals can be processed.
More detailed descriptions of the circuit operation can be
found in: Technical Paper STP 97-10, Monolithic Magnetic
Hall Sensor Using Dynamic Quadrature Offset Cancellation
and Technical Paper STP 99-1, Chopper-Stabilized Amplifiers
With A Track-and-Hold Signal Demodulator.
Operation. The output of these devices switches low (turns
on) when a magnetic field perpendicular to the Hall sensor
exceeds the operate point threshold (BOP). After turn-on, the
output is capable of sinking 25 mA and the output voltage is
V
OUT(SAT)
. Note that the device latches; that is, a south pole of
sufficient strength towards the branded surface of the device
will turn the device on; removal of the south pole will leave the
device on. When the magnetic field is reduced below the
release point (BRP), the device output goes high (turns off). The
difference in the magnetic operate and release points is 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.
Applications. It is strongly recommended that an external
bypass capacitor be connected (in close proximity to the Hall
sensor) between the supply and ground of the device to reduce
both external noise and noise generated by the chopperstabilization technique.
The simplest form of magnet that will operate these devices
is a ring magnet. Other methods of operation, such as linear
magnets, are possible. Extensive applications information on
magnets and Hall-effect sensors is also available in the Allegro
Electronic Data Book AMS-702 or Application Note 27701, or
www.allegromicro.com
Dwg. EH-012
REG
SAMPLE
& HOLD
X
+V
HALL
VOLTAGE
B
+
—
Dwg. AH-011-2
+B
0
OUTPUT VOLTAGE
FLUX DENSITY
Dwg. GH-007-2
0
RP
B
V
OUT(SAT)
CC
V
OP
B
+V
SUPPLY
OUTPUT
Dwg. EH-013
0.1 µF
SUPPLY
1
V
CC
3
2
X
PTCT
Page 9
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
www.allegromicro.com
9
PACKAGE DESIGNATOR ‘LH’
(fits SC-74A solder-pad layout)
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. Where no tolerance is specified, dimension is nominal.
5. Add "LT" to part number for tape and reel.
Dimensions in Inches
(for reference only)
Dimensions in Millimeters
(controlling dimensions)
Dwg. MA-011-3 in
12
0.039
0.094
0.03
7
0.028
3
Dwg. MA-011-3 mm
12
1.00
2.40
0.95
0.70
3
Dwg. MA-010-3B in
12
0.006
0.000
0.0079
0.0050
0.122
0.114
0.083
0.073
0.118
0.106
0.037
BSC
0.022
REF
0.020
0.012
3
0° TO 8°
0.020
MIN
0.043
0.035
0.049
0.035
Dwg. MA-010-3B mm
12
0.15
0.00
0.20
0.127
3.10
2.90
2.10
1.85
3.00
2.70
0.95
BSC
0.55
REF
0.50
0.30
3
0° TO 8°
0.25
MIN
1.10
0.90
1.25
0.90
Page 10
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
10
PACKAGE DESIGNATOR ‘LT’
(SOT-89/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.
Dwg. MA-009-3A in
1
23
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
23
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
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 SOT-89 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
13
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 SOT-89 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
Page 11
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
www.allegromicro.com
11
Surface-Mount Lead Form (order A3240xUA-TL)
Dimensions in Inches
(controlling dimensions)
Dimensions in Millimeters
(for reference only)
PACKAGE DESIGNATOR ‘UA’
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. Supplied in bulk pack (500 pieces per bag).
0.095
±0.005
0.020
MIN
FLAT
Dwg. MH-015 in
0.004
MAX
0.002
MAX
0°–8°
2.41
±0.13
0.51
MIN
FLAT
Dwg. MH-015 mm
0.10
MAX
0.051
MAX
0°–8°
Dwg. MH-014E in
0.164
0.159
0.062
0.058
0.0173
0.0138
0.050
BSC
45°
0.640
0.600
0.0189
0.0142
0.085
MAX
45°
0.031
123
0.122
0.117
SEE NOTE
Dwg. MH-014E mm
4.17
4.04
1.57
1.47
0.44
0.35
1.27
BSC
45°
16.26
15.24
0.48
0.36
2.16
MAX
45°
0.79
123
3.10
2.97
SEE NOTE
Page 12
3240
CHOPPER-STABILIZED,
PRECISION
HALL-EFFECT SWITCH
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
12
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.
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