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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Features and Benefits
Resistant to physical stress Superior temperature stability Output short-circuit protection Operation from unregulated supply Reverse battery protection Solid-state reliability Small size
Description
The A3340 Hall effect switch is an extremely temperature-stable and stress-resistant sensor especially suited for operation over extended temperature ranges up to 150C. 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 off. An on-board regulator permits operation with supply voltages of 4.2 to 24 volts.
Packages: 3 pin SOT23W (suffix LH), and 3 pin SIP (suffix UA)
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. The A3340 complements the A3240, which offers the same features, but with the opposite output polarity.
Not to scale
Functional Block Diagram
VCC
Regulator To All Subcircuits Sample and Hold Dynamic Offset Cancellation
VOUT
Amp
Amp
Control
Current Limit <1
GND
A3340-DS, Rev. 1
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Selection Guide
Part Number A3340ELHLT-T A3340EUA-T A3340LLHLT-T A3340LUA-T Packing* 7-in. reel, 3000 pieces/reel Bulk, 500 pieces/bag 7-in. reel, 3000 pieces/reel Bulk, 500 pieces/bag Mounting 3-pin SOT23W surface mount 3-pin SIP through hole 3-pin SOT23W surface mount 3-pin SIP through hole Ambient, TA -40C to 85C 5 -40C to 150C 50 BRP (Min) BOP (Max)
*Contact Allegro for additional packing options.
Absolute Maximum Ratings
Characteristic Supply Voltage Reverse Supply Voltage Output Off Voltage Reverse Output Voltage Continuous Output Current Reverse Output Current Magnetic Flux Density Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Symbol VCC VRCC VOUT VROUT IOUT IROUT
B
Notes
Rating 26.5 -30 26 -0.5
Units V V V V mA mA G C C C C
Internal current limiting (intended to protect the device from output short circuits)
25 -50 Unlimited
TA TJ(max) Tstg
Range E Range L
-40 to 85 -40 to 150 165 -65 to 170
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Operating Characteristics, valid over TA, unless otherwise noted
Characteristic Electrical Characteristics Supply Voltage Range2 Output Leakage Current Output Saturation Voltage Output Current Limit Power-On Time Chopping Frequency Output Rise Time Output Fall Time Supply Current Reverse Battery Current Zener Voltage Zener Impedance Magnetic Release
1Typical
Symbol VCC IOFF VOUT(SAT) IOM tPO fC tr tf ICC IRCC VZD ZZD BOP BRP Bhys BOP - BRP
Test Conditions Operating, TJ < 165C VOUT = 24 V, B > BOP IOUT = 20 mA, B < BRP B > BOP VCC > 4.2 V RLOAD = 820 , CLOAD = 20 pF RLOAD = 820 , CLOAD = 20 pF B < BRP, VCC = 12 V B > BOP, VCC = 12 V VRCC = -30 V VZ + VD, ICC = 15 mA, TA = 25C ZZ + ZD, ICC = 15 mA, TA = 25C
Min. 4.2 - - 30 - - - - - - - 28 - - 5.0 -
Typ.1 - - 185 - - 340 0.2 0.1 3.0 4.0 - 32 50 35 25 6
Max. 24 10 500 60 50 - 2.0 2.0 6.0 6.0 -5.0 37 - 50 - -
Units V A mV mA s kHz s s mA mA mA V G G G
Characteristics3
Operate Point4 Point4 Hysteresis
data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as TA = 25C 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
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic Symbol Test Conditions Package LH, 1-layer PCB with copper limited to solder pads Package Thermal Resistance RJA Package LH, 2-layer PCB with 0.463 in.2 of copper area each side connected by thermal vias Package UA, 1-layer PCB with copper limited to solder pads Value Units 228 110 165 C/W C/W C/W
25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 20
Power Derating Curve TJ(max) = 165C; ICC = ICC(max)
VCC(max)
Maximum Allowable VCC (V)
Package LH, 2-layer PCB (R JA = 110 C/W) Package UA, 1-layer PCB (R JA = 165 C/W) Package LH, 1-layer PCB (R JA = 228 C/W)
VCC(min)
120 140 160 180
40
60
80
100
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 20
Power Dissipation, PD (mW)
Pa (R cka ge JA = 1 LH 10 , 2Pac C lay /W er (R kage PC ) UA JA = B , 1165 C/ la yer W) PC B
Pac k (R age LH ,1 JA = 2 28 -layer PCB C/W )
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
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
TYPICAL OPERATING CHARACTERISTICS as a function of temperature
SWITCH POINTS
50
40
SWITCH POINTS IN GAUSS
OPERATE POINT
30
RELEASE POINT
20
10
VCC = 4.5 V VCC = 24 V
0 -50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN C
Dwg. GH-026-5
OUTPUT SATURATION VOLTAGE
300
SUPPLY CURRENT
6.0
IOUT = 20 mA VCC = 12 V
VCC = 12 V
SATURATION VOLTAGE IN mV
5.0
200
SUPPLY CURRENT IN mA
4.0
OUTPUT ON, B < BRP
100
3.0
OUTPUT OFF, B > BOP
0 -50
-25
0
25
50
75
100
125
150
2.0 -50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN C
Dwg. GH-029-4
AMBIENT TEMPERATURE IN C
Dwg. GH-028-5
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
TYPICAL OPERATING CHARACTERISTICS as a function of supply voltage
SWITCH POINTS
40
OPERATE POINT
30
SWITCH POINT IN GAUSS
RELEASE POINT
20
TA = 150C TA = -40C
10
0 3.0
3.5
4.0
4.5
5.0
24
Dwg. GH-021-2
SUPPLY VOLTAGE IN VOLTS
OUTPUT SATURATION VOLTAGE
250
IOUT = 20 mA TA = 150C TA = +25C TA = -40C
SUPPLY CURRENT
8.0 7.0 6.0
OUTPUT ON TA = 150C TA = +25C TA = -40C
SATURATION VOLTAGE IN mV
225
SUPPLY CURRENT IN mA
5.0 4.0 3.0 2.0 1.0
200
175
150 3.0
3.5
4.0
4.5
5.0
24
Dwg. GH-055-1
0 3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
11
12
SUPPLY VOLTAGE IN VOLTS
SUPPLY VOLTAGE IN VOLTS
Dwg. GH-058-4
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
FUNCTIONAL DESCRIPTION
REG
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. 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. 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.
X
+V C C
B +VHALL
-V HALL
+V
VCC
OUT P UT V OL T A G E
B RP
B OP
V OUT (S AT )
0 0 F L UX DE NS IT Y +B
SUPPLY
VOUT
OUTPUT
PTCT
GND 0.1 F
X
VCC
Dwg. EH-013
SAMPLE & HOLD
Dwg. EH-012
SUPPLY
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Package LH, 3-Pin (SOT-23W)
2.975 1.49 B 3
A
0.28
4 0.180
0.96 B 2.90 1.91
B
0.38
1
2 0.25
10
Seating Plane Gauge Plane 1.00 All dimensions nominal, not for tooling use Dimensions in millimeters 0.05
A B
10
0.95
0.40
Active Area Depth Hall element, not to scale
Pin-out Diagrams
Package LH
G
3
Package UA
X
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
X
PTCT 1 2
PTCT
1
2
3
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Package UA, 3-Pin SIP
.161 [4.09]
45
A
.0195 [0.50]
B .081 2.06 B
.060 [1.52] .057 1.45
.119 [3.02]
B
45
.085 [2.16] MAX
.031 [0.79]
.016 [0.41]
.590 [14.99]
1
2
3
.017 [0.43] .050 [1.27]
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 (c)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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