A3340: Chopper-Stabilized, Precision Hall-Effect Switch

A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Discontinued Product
This device is no longer in production. The device should not be
purchased for new design applications. Samples are no longer available.
Date of status change: November 1, 2010
Recommended Substitutions:
For existing customer transition, and for new customers or new applications, refer to the A1125.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan
for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. 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 which may result from its use.
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 IC 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. 8
A3340
Chopper-Stabilized, Precision Hall-Effect Switch
Selection Guide
Packing1
Part Number
Mounting
Ambient, TA
A3340EUA-T2
Bulk, 500 pieces/bag
3-pin SIP through hole
–40ºC to 85ºC
A3340LUA-T2
Bulk, 500 pieces/bag
3-pin SIP through hole
–40ºC to 150ºC
BRP (Min)
BOP (Max)
5
50
1Contact Allegro
for additional packing options.
is in production but has been determined to be LAST TIME BUY. This classification indicates that the variant is obsolete and notice has been
given. Sale of the variant is currently restricted to existing customer applications. The variant should not be purchased for new design applications
because of obsolescence in the near future. Samples are no longer available. Status date change May 3, 2010. Deadline for receipt of LAST TIME
BUY orders is October 29, 2010.
2Variant
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Units
Supply Voltage
VCC
26.5
V
Reverse Supply Voltage
VRCC
–30
V
Output Off Voltage
VOUT
26
V
Reverse Output Voltage
VROUT
–0.5
V
25
mA
–50
mA
Continuous Output Current
IOUT
Reverse Output Current
IROUT
Magnetic Flux Density
Internal current limiting (intended to protect the
device from output short circuits)
Unlimited
G
Range E
–40 to 85
ºC
Range L
B
Operating Ambient Temperature
TA
–40 to 150
ºC
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
–
270
500
mV
Output Current Limit
IOM
B < BRP
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).
4B
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
SWITCHPOINTS
VCC = 12 V
50
OUTPUT SATURATION VOLTAGE
VCC = 12 V, IOUT= 20 mA
500
450
400
SATURATION VOLTAGE IN mV
SWITCH POINTS IN GAUSS
40
BOP
30
BRP
20
10
350
300
250
200
150
100
50
0
-50
-25
0
25
50
75
100
125
0
-50
150
-25
AMBIENT TEMPERATURE IN oC
SUPPLY CURRENT
B > BOP
6.0
25
50
75
100
125
150
125
1 50
SUPPLY CURRENT
B < BRP
6.0
5.0
SUPPLY CURRENT IN mA
5.0
SUPPLY CURRENT IN mA
0
AMBIENT TEMPERATURE IN oC
VCC = 24 V
4.0
VCC = 12 V
VCC = 4.2 V
3.0
4.0
VCC = 24 V
VCC = 12 V
3.0
VCC = 4.2 V
2.0
-50
-25
0
25
50
75
AMBIENT TEMPERATURE IN o C
100
125
150
2.0
-50
-25
0
25
50
75
100
AMBIENT TEMPERATURE IN o C
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
SWITCHPOINTS
TA = 25°C
50
SWITCH POINTS IN GAUSS
40
BOP
30
BRP
20
10
0
2
4
6
8
10
12
14
16
18
20
22
24
SUPPLY VOLTAGE IN VOLTS
OUTPUT SATURATION VOLTAGE
IOUT = 20 mA
500
6.0
450
5.5
TA = 150°C
400
5.0
350
SUPPLY CURRENT IN mA
SATURATION VOLTAGE IN mV
SUPPLY CURRENT
B > BOP
TA = 25°C
300
250
TA = –40°C
200
150
TA = –40°C
4.5
TA = 25°C
4.0
3.5
TA = 150°C
3.0
100
2.5
50
0
2.0
2
4
6
8
10
12
14
16
18
SUPPLY VOLTAGE IN VOLTS
20
22
24
2
4
6
8
10
12
14
16
18
20
22
24
SUPPLY VOLTAGE IN VOLTS
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 Sensing
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 element 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 element) between the
supply and ground of the device to reduce both external noise and
noise generated by the chopper stabilization 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 maintaining the Hall-voltage
signal that is induced by the external magnetic flux. The signal
is then captured by a sample-and hold 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 devices 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)
+0.12
2.98 –0.08
1.49 D
4°±4°
3
A
+0.020
0.180–0.053
0.96 D
+0.10
2.90 –0.20
+0.19
1.91 –0.06
2.40
0.70
D
0.25 MIN
1.00
2
1
0.55 REF
0.25 BSC
0.95
Seating Plane
Gauge Plane
B
PCB Layout Reference View
Branded Face
8X 10° REF
1.00 ±0.13
NNT
+0.10
0.05 –0.05
0.95 BSC
1
C
0.40 ±0.10
N = Last two digits of device part number
T = Temperature code
For Reference Only; not for tooling use (reference dwg. 802840)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A
Active Area Depth, 0.28 mm REF
B
Reference land pattern layout
All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances
C
Branding scale and appearance at supplier discretion
D
Hall element, not to scale
Pin-out Diagrams
Package UA
GND
Package LH
Standard Branding Reference View
X
3
PTCT
X
VCC
VOUT
GND
3
GND
VOUT
Terminal List
Name
2
2
C
1
1
VCC
PTCT
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
+0.08
4.09 –0.05
45°
B
C
E
2.06
1.52 ±0.05
1.45 E
Mold Ejector
Pin Indent
+0.08
3.02 –0.05
E
Branded
Face
45°
1
2.16
MAX
D Standard Branding Reference View
= Supplier emblem
N = Last two digits of device part number
T = Temperature code
0.79 REF
A
0.51
REF
NNT
1
2
3
+0.03
0.41 –0.06
15.75 ±0.51
For Reference Only; not for tooling use (reference DWG-9049)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A
Dambar removal protrusion (6X)
B Gate burr area
C Active Area Depth, 0.50 mm REF
+0.05
0.43 –0.07
D
Branding scale and appearance at supplier discretion
E
Hall element, not to scale
1.27 NOM
Copyright ©2004-2010, Allegro MicroSystems, Inc.
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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