Allegro A3340 Chopper-stabilized, precision hall-effect switch Datasheet

A3340
Chopper-Stabilized, Precision
Hall-Effect Switch
Features and Benefits
Description
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The A3340 Hall effect switch is an extremely temperature-stable
and stress-resistant sensor especially suited for operation
over extended temperature ranges up 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.
Resistant to physical stress
Superior temperature stability
Output short-circuit protection
Operation from unregulated supply
Reverse battery protection
Solid-state reliability
Small size
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 off. An on-board regulator
permits operation with supply voltages of 4.2 to 24 volts.
Two package styles provide a magnetically optimized package
for most applications. Suffix LH is an SOT23W surface mount
package and while suffix UA is a three-lead ultramini SIP for
through hole mounting.
Packages: 3 pin SOT23W (suffix LH),
and 3 pin SIP (suffix UA)
The A3340 complements the A3240, which offers the same
features, but with the opposite output polarity.
Not to scale
Functional Block Diagram
VCC
Regulator
Amp
Sample and Hold
Dynamic Offset
Cancellation
To All Subcircuits
Amp
VOUT
Control
Current Limit
<17
GND
A3340-DS, Rev. 1
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Selection Guide
Part Number
Packing*
Mounting
Ambient, TA
A3340ELHLT-T
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A3340EUA-T
Bulk, 500 pieces/bag
3-pin SIP through hole
A3340LLHLT-T
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A3340LUA-T
Bulk, 500 pieces/bag
3-pin SIP through hole
BRP (Min)
BOP (Max)
5
50
–40ºC to 85ºC
–40ºC to 150ºC
*Contact Allegro for additional packing options.
Absolute Maximum Ratings
Rating
Units
Supply Voltage
Characteristic
Symbol
VCC
Notes
26.5
V
Reverse Supply Voltage
VRCC
–30
V
Output Off Voltage
VOUT
26
V
Reverse Output Voltage
VROUT
–0.5
V
25
mA
Internal current limiting (intended to protect the
device from output short circuits)
Continuous Output Current
IOUT
Reverse Output Current
IROUT
–50
mA
B
Unlimited
G
Magnetic Flux Density
Range E
–40 to 85
ºC
Range L
–40 to 150
ºC
Operating Ambient Temperature
TA
Maximum Junction Temperature
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Storage Temperature
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Operating Characteristics, valid over TA, unless otherwise noted
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Units
Electrical Characteristics
Supply Voltage Range2
VCC
Operating, TJ < 165°C
4.2
–
24
V
Output Leakage Current
IOFF
VOUT = 24 V, B > BOP
–
–
10
μA
VOUT(SAT)
Output Saturation Voltage
IOUT = 20 mA, B < BRP
–
185
500
mV
Output Current Limit
IOM
B > BOP
30
–
60
mA
Power-On Time
tPO
VCC > 4.2 V
–
–
50
μs
Chopping Frequency
fC
–
340
–
kHz
Output Rise Time
tr
RLOAD = 820 Ω, CLOAD = 20 pF
–
0.2
2.0
μs
Output Fall Time
tf
RLOAD = 820 Ω, CLOAD = 20 pF
–
0.1
2.0
μs
Supply Current
ICC
B < BRP, VCC = 12 V
–
3.0
6.0
mA
B > BOP, VCC = 12 V
–
4.0
6.0
mA
Reverse Battery Current
IRCC
VRCC = –30 V
–
–
-5.0
mA
Zener Voltage
VZD
VZ + VD, ICC = 15 mA, TA = 25°C
28
32
37
V
Zener Impedance
ZZD
ZZ + ZD, ICC = 15 mA, TA = 25°C
–
50
–
Ω
Magnetic
Characteristics3
Operate Point4
BOP
–
35
50
G
Point4
BRP
5.0
25
–
G
–
6
–
G
Release
Hysteresis
Bhys
BOP – BRP
1Typical
data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as TA = 25°C and VCC =
12 V. Performance may vary for individual units, within the specified maximum and minimum limits.
2Maximum voltage must be adjusted for power dissipation and junction temperature.
31 G (gauss) = 0.1 mT (millitesla).
3B
OP = operate point (output turns off); BRP = release point (output turns on).
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions
RθJA
Maximum Allowable VCC (V)
Package Thermal Resistance
Value Units
Package LH, 1-layer PCB with copper limited to solder pads
228
ºC/W
Package LH, 2-layer PCB with 0.463 in.2 of copper area each
side connected by thermal vias
110
ºC/W
Package UA, 1-layer PCB with copper limited to solder pads
165
ºC/W
Power Derating Curve
TJ(max) = 165ºC; ICC = ICC(max)
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
VCC(max)
Package LH, 2-layer PCB
(RQJA = 110 ºC/W)
Package UA, 1-layer PCB
(RQJA = 165 ºC/W)
Package LH, 1-layer PCB
(RQJA = 228 ºC/W)
20
40
60
80
100
VCC(min)
120
140
160
180
Power Dissipation, PD (mW)
Power Dissipation versus Ambient Temperature
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
Pa
(R cka
ge
QJ
A =
L
11 H, 2
0 º -la
Pac
C/ ye
W
(R kage
) r PC
UA
QJA =
B
,
165 1-la
ºC/ yer
W)
PC
B
Pac
k
(R age LH
,
QJA =
228 1-laye
ºC/W r PC
B
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
TYPICAL OPERATING CHARACTERISTICS
as a function of temperature
SWITCH POINTS
50
SWITCH POINTS IN GAUSS
40
OPERATE POINT
30
RELEASE POINT
20
VCC = 4.5 V
VCC = 24 V
10
0
-50
-25
0
25
50
75
100
125
AMBIENT TEMPERATURE IN °C
150
Dwg. GH-026-5
OUTPUT SATURATION VOLTAGE
SUPPLY CURRENT
300
6.0
IOUT = 20 mA
VCC = 12 V
5.0
SUPPLY CURRENT IN mA
SATURATION VOLTAGE IN mV
VCC = 12 V
200
100
0
-50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN ° C
4.0
3.0
2.0
-50
OUTPUT ON, B < BRP
OUTPUT OFF, B > BOP
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN ° C
Dwg. GH-029-4
Dwg. GH-028-5
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
TYPICAL OPERATING CHARACTERISTICS
as a function of supply voltage
SWITCH POINTS
40
OPERATE POINT
SWITCH POINT IN GAUSS
30
RELEASE POINT
TA = 150°C
TA = -40°C
20
10
0
3.0
3.5
4.0
4.5
24
5.0
SUPPLY VOLTAGE IN VOLTS
Dwg. GH-021-2
OUTPUT SATURATION VOLTAGE
SUPPLY CURRENT
250
8.0
OUTPUT ON
TA = 150°C
TA = +25°C
TA = -40°C
7.0
225
6.0
SUPPLY CURRENT IN mA
SATURATION VOLTAGE IN mV
IOUT = 20 mA
TA = 150°C
TA = +25°C
TA = -40°C
200
175
5.0
4.0
3.0
2.0
1.0
150
3.0
3.5
4.0
4.5
5.0
24
0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
SUPPLY VOLTAGE IN VOLTS
SUPPLY VOLTAGE IN VOLTS
Dwg. GH-055-1
10
11
12
Dwg. GH-058-4
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
FUNCTIONAL DESCRIPTION
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-andHold Signal Demodulator. Operation. The output of these devices
switches high (turns off) when a magnetic field (south pole)
perpendicular to the Hall sensor exceeds the operate point threshold (BOP). When the magnetic field is reduced below the release
point (BRP), the device output goes low (turns on). After turn-on,
the output is capable of sinking 25 mA and the output voltage is
VOUT(SAT). The difference in the magnetic operate and release
points is the hysteresis (Bhys) 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.
X
B
+V C C
Dwg. EH-012
+VHALL
–V HALL
+V
VCC
OUT P UT V OL T A G E
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 Hallvoltage 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.
SAMPLE
& HOLD
REG
B RP
B OP
V OUT (S AT )
0
0
+B
F L UX DE NS IT Y
SUPPLY
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 Application Note 27701, or
at www.allegromicro.com.
OUTPUT
PTCT
VOUT
GND
X
0.1 μF
VCC
SUPPLY
Dwg. EH-013
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
7
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Package LH, 3-Pin (SOT-23W)
2.975
1.49 B
A
3
4º
0.28
0.180
0.96 B
2.90
1.91
B
0.38
2
1
0.25
Seating Plane
Gauge Plane
10º
1.00
10º
0.95
0.40
All dimensions nominal, not for tooling use
Dimensions in millimeters
0.05
A
Active Area Depth
B
Hall element, not to scale
Pin-out Diagrams
Package UA
G
Package LH
3
X
X
PTCT
PTCT
1
2
1
2
3
Terminal List
Name
VCC
VOUT
GND
Description
Connects power supply to chip
Output from circuit
Ground
Number
Package LH Package UA
1
1
2
3
3
2
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Package UA, 3-Pin SIP
.161 [4.09]
45°
A
.0195 [0.50]
B .081 2.06
.060 [1.52]
B
.057 1.45
.119 [3.02]
45°
B
.085 [2.16]
MAX
.031 [0.79]
.016 [0.41]
.590 [14.99]
1
.017 [0.43]
.050 [1.27]
2
3
All dimensions nominal, not for tooling use
Dimensions in inches, metric dimensions (mm) in brackets, for reference only
A Active Area Depth
B Hall element (not to scale)
Copyright ©2004, 2007, Allegro MicroSystems, Inc.
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’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use;
nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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