A3241ELHLT-T [ALLEGRO]
Chopper-Stabilized Unipolar Hall-Effect Switches; 稳定斩波型单极霍尔效应开关
| 型号： | A3241ELHLT-T |
| 厂家： | 
ALLEGRO MICROSYSTEMS |
| 描述： | Chopper-Stabilized Unipolar Hall-Effect Switches |
| 文件： | 总12页 (文件大小：402K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A3241 and A3242
Chopper-Stabilized
Unipolar Hall-Effect Switches
The A3241 and A3242 integrated circuits are unipolar Hall-effect switches with
digital outputs. These sensors are suited for operation over extended temperature
ranges, up to +150°C. Superior high-temperature performance is made pos-
sible through an Allegro® patented dynamic offset cancellation, which reduces
the residual offset voltage normally caused by device overmolding, temperature
excursions, and thermal stress.
Package LH, 3-pin Surface Mount
3
The A3241 and A3242 Hall-effect switches include the following on a single
silicon chip: voltage regulator, Hall-voltage generator, small-signal amplifier,
chopper stabilization, Schmitt trigger, and a short circuit protected open-drain
output. Advanced BiCMOS wafer fabrication processing is used to take advantage
of low-voltage requirements, component matching, very low input-offset errors,
and small component geometries.
1
3
2
1
2
The integrated voltage regulator permits operation from 3.6 to 24 V. The unipolar
family members operate with a sufficient south polarity field only, turning off in
the absence of such a south polarity field.
Package UA, 3-pin SIP
The A3241 and A3242 are rated for operation between the ambient temperatures
–40°C and 85°C for the E temperature range, and –40°C to 150°C for the L tem-
perature range. The small geometries of the BiCMOS process allow these devices
to be provided in ultrasmall packages. The package styles available provide mag-
netically optimized solutions for most applications. Package LH is an SOT23W,
a miniature low-profile surface-mount package, while package UA is a three-lead
ultramini SIP for through-hole mounting. Each package is available in a lead (Pb)
free version, with 100% matte tin plated leadframes.
1
2
3
1
2
Features and Benefits
3
ꢀChopper stabilization
ꢀOutput short circuit protection
ꢀSolid state reliability
ꢀSmall size
ABSOLUTE MAXIMUM RATINGS
ꢀSuperior temperature stability
ꢀExtremely low switchpoint drift
ꢀInsensitive to physical stress
Supply Voltage, VCC ..........................................28 V
Reverse-Supply Voltage, VRCC ........................–18 V
Reverse-Supply Current, IRCC ........................–2 mA
Output Off Voltage, VOUT..................................28 V
Output Current, IOUTSINK........... Internally Limited
Magnetic Flux Density, B .........................Unlimited
Operating Temperature
Ambient, TA, Range E..................–40ºC to 85ºC
Ambient, TA, Range L................–40ºC to 150ºC
Maximum Junction, TJ(MAX)......................165ºC
Storage Temperature, TS ..................–65ºC to 170ºC
ꢀRobust EMC capability
ꢀHigh ESD ratings (HBM)
ꢀReverse battery protection
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241-DS, Rev. 2
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Product Selection Guide
Pb-
free
Ambient, TA
(°C)
BRP(MIN) BOP(MAX)
Part Number
Packing*
Mounting
(G)
(G)
A3241ELHLT
A3241ELHLT-T
A3241EUA
–
Yes
–
7-in. reel, 3000 pieces/reel
Bulk, 500 pieces/bag
3-pin SOT23W surface mount
3-pin SIP through hole
–40 to 85
–40 to 150
–40 to 85
–40 to 150
A3241EUA-T
A3241LLHLT
A3241LLHLT-T
A3241LUA
Yes
–
40
135
7-in. reel, 3000 pieces/reel
Bulk, 500 pieces/bag
3-pin SOT23W surface mount
3-pin SIP through hole
Yes
–
A3241LUA-T
A3242ELHLT
A3242ELHLT-T
A3242EUA
Yes
–
7-in. reel, 3000 pieces/reel
Bulk, 500 pieces/bag
3-pin SOT23W surface mount
3-pin SIP through hole
Yes
–
A3242EUA-T
A3242LLHLT
A3242LLHLT-T
A3242LUA
Yes
–
110
200
7-in. reel, 3000 pieces/reel
Bulk, 500 pieces/bag
3-pin SOT23W surface mount
3-pin SIP through hole
Yes
–
A3242LUA-T
Yes
*Contact Allegro for additional packing options.
Functional Block Diagram
VCC
Regulator
To All Subcircuits
VOUT
Amp
Amp
Control
Current Limit
<1Ω
GND
Terminal List
Number
Name
Description
Package LH
Package UA
VCC
VOUT
GND
Connects power supply to chip
Output from circuit
Ground
1
2
3
1
3
2
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
OPERATING CHARACTERISTICS valid over full operating voltage and ambient temperature ranges, unless otherwise noted
Characteristic
Electrical Characteristics
Supply Voltage1
Symbol
Test Conditions
Min.
Typ.
Max. Units
VCC
IOUTOFF
VOUT(SAT)
IOM
Operating, TJ < 165°C
3.6
–
–
–
24
10
500
60
50
–
V
Output Leakage Current
Output On Voltage
Output Current Limit
Power-On Time
VOUT = 24 V, B < BRP
IOUT = 20 mA, B > BOP
B > BOP
μA
mV
mA
μs
–
–
30
–
–
tPO
VCC > VCC(MIN)
–
Chopping Frequency
Output Rise Time2
Output Fall Time2
fc
–
200
–
kHz
μs
tr
RLOAD = 820 Ω, CS = 20 pF
RLOAD = 820 Ω, CS = 20 pF
B > BOP
–
1
tf
–
–
1
μs
ICCON
ICCOFF
IRCC
–
1.5
1.5
–
3.5
3.5
–2
mA
mA
mA
Supply Current
B < BRP
–
Reverse Battery Current
VRCC = –18 V
–
Supply Zener Clamp Voltage
VZSupply
IZSupply
ICC = 6.5 mA; TA = 25°C
VS = 28 V
28
–
–
–
–
V
Supply Zener Current3
6.5
mA
Magnetic Characteristics4
G
G
G
G
G
G
A3241
A3242
A3241
A3242
A3241
50
120
40
95
150
70
135
200
110
190
42
Operate Point
Release Point
Hysteresis
BOP
BRP
110
10
125
25
BHYS
BOP – BRP
A3242
10
25
40
1 Maximum voltage must be adjusted for power dissipation and junction temperature, see Power Derating section.
2 CS = oscilloscope probe capacitance.
3 Maximum current limit is equal to the maximum ICC(MAX) + 3 mA.
4 Magnetic flux density, B, is indicated as a negative value for north-polarity magnetic fields, and as a positive value for south-polarity magnetic fields.
This so-called algebraic convention supports arithmetic comparison of north and south polarity values, where the relative strength of the field is indicated
by the absolute value of B, and the sign indicates the polarity of the field (for example, a –100 G field and a 100 G field have equivalent strength, but
opposite polarity).
DEVICE QUALIFICATION PROGRAM
Contact Allegro for information.
EMC (Electromagnetic Compatibility) REQUIREMENTS
Contact Allegro for information.
Allegro MicroSystems, Inc.
3
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Characteristic Data
Supply Current (On) versus Ambient Temperature
Supply Current (On) versus Supply Voltage
5.0
4.0
3.0
2.0
1.0
0.0
5.0
4.0
3.0
2.0
1.0
0
TA (°C)
–40
VCC (V)
24
25
3.6
150
-50
0
50
100
150
0
5
10
15
20
25
TA (°C)
VCC (V)
Supply Current (Off) versus Ambient Temperature
Supply Current (Off) versus Supply Voltage
5.0
4.0
3.0
2.0
1.0
0.0
5.0
4.0
3.0
2.0
1.0
0
TA (°C)
–40
25
VCC (V)
24
3.6
150
0
5
10
15
20
25
-50
0
50
100
150
VCC (V)
TA (°C)
Output Voltage (On) versus Ambient Temperature
Output Voltage (On) versus Supply Voltage
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
VCC (V)
24
TA (°C)
–40
3.6
25
150
0
0
-50
0
50
100
150
0
5
10
15
20
25
TA (°C)
VCC (V)
Continued on the next page...
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A3241-DS, Rev. 2
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Operate Point versus Supply Voltage
(A3241)
Operate Point versus Ambient Temperature
(A3241)
130
120
110
100
90
130
120
110
100
90
TA (°C)
–40
VCC (V)
24
25
3.6
150
80
80
70
70
60
60
50
50
0
5
10
15
20
25
25
25
-50
0
50
100
150
150
150
VCC (V)
TA (°C)
Release Point versus Supply Voltage
(A3241)
Release Point versus Ambient Temperature
(A3241)
110
100
90
110
100
90
TA (°C)
–40
80
VCC (V)
24
80
25
70
70
3.6
150
60
60
50
50
40
40
0
5
10
15
20
-50
0
50
100
VCC (V)
TA (°C)
Hysteresis versus Supply Voltage
(A3241)
Hysteresis versus Ambient Temperature
(A3241)
40
35
30
25
20
15
10
40
35
30
25
20
15
10
VCC (V)
24
TA (°C)
–40
3.6
25
150
0
5
10
15
20
-50
0
50
100
VCC (V)
TA (°C)
Allegro MicroSystems, Inc.
5
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Operate Point versus Supply Voltage
(A3242)
Operate Point versus Ambient Temperature
(A3242)
200
190
180
170
160
150
140
130
120
200
190
180
170
160
150
140
130
120
TA (°C)
–40
VCC (V)
24
25
3.6
150
-50
0
50
100
150
150
150
0
5
10
15
20
25
25
25
TA (°C)
VCC (V)
Release Point versus Ambient Temperature
(A3242)
Release Point versus Supply Voltage
(A3242)
190
180
170
160
150
140
130
120
110
190
180
170
160
150
140
130
120
110
TA (°C)
–40
VCC (V)
24
25
3.6
150
-50
0
50
100
0
5
10
15
20
TA (°C)
VCC (V)
Hysteresis versus Supply Voltage
(A3242)
Hysteresis versus Ambient Temperature
(A3242)
40
35
30
25
20
15
10
40
35
30
25
20
15
10
VCC (V)
24
TA (°C)
–40
3.6
25
150
0
5
10
15
20
-50
0
50
100
VCC (V)
TA (°C)
Allegro MicroSystems, Inc.
6
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions
Value
Units
Package LH-3, 1-layer PCB with copper limited to
solder pads
110
ºC/W
Package LH-3, 2-layer PCB with 0.926 in2 on each
side, connected by thermal vias
RθJA
Package Thermal Resistance
228
165
ºC/W
ºC/W
Package UA, 1-layer PCB with copper limited to
solder pads
Power Derating Curve
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
VCC(max)
1-layer PCB, Package LH
(RθJA= 110 °C/W)
1-layer PCB, Package UA
(RθJA= 165 °C/W)
8
7
6
5
2-layer PCB, Package LH
(RθJA= 228 °C/W)
4
3
2
VCC(min)
100 120 140 160 180
Temperature (°C)
20
40
60
80
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
40
60
80
100
120
140
160
180
Temperature (°C)
Allegro MicroSystems, Inc.
7
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Functional Description
Operation
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 chopper stabilization technique. As is
shown in Panel B of figure 1, a 0.1μF capacitor is typical.
The output of these devices switches low (turns on) when a
magnetic field (south polarity) perpendicular to the Hall sen-
sor exceeds the operate point threshold, BOP. After turn-on, the
output voltage is VOUT(SAT). The output transistor is capable of
sinking current up to the short circuit current limit, IOM, which
is a minimum of 30 mA. 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, 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.
Extensive applications information on magnets and Hall-effect
sensors is available in:
• Hall-Effect IC Applications Guide, AN27701,
• Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead
Welding and Lead Forming, AN27703.1
• Soldering Methods for Allegro’s Products – SMT and Through-
Hole, AN26009
Powering-on the device in the hysteresis region, less than BOP
and higher than BRP, allows an indeterminate output state. The
correct state is attained after the first excursion beyond BOP or
BRP.
All are provided in Allegro Electronic Data Book, AMS-702 and
the Allegro Web site: www.allegromicro.com
(A)
(B)
VS
V+
VCC
VCC
RLOAD
Sensor Output
C
BYP
A324x
VOUT
0.1 μF
GND
VOUT(SAT)
0
B+
B–
0
BHYS
Figure 1: Switching Behavior of Unipolar Switches. In Panel A, on the horizontal axis, the B+ direction indicates increasing south polarity
magnetic field strength, and the B– direction indicates decreasing south polarity field strength (including the case of increasing north
polarity). This behavior can be exhibited when using a circuit such as that shown in panel B.
Allegro MicroSystems, Inc.
8
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
The chopper stabilization technique uses a 200 kHz high-fre-
Chopper Stabilization Technique
quency clock. For demodulation process, a sample and hold
technique is used, where the sampling is performed at twice the
chopper frequency (400 kHz). This high-frequency operation
allows a greater sampling rate, which results in higher accuracy
and faster signal-processing capability. This approach desensi-
tizes the chip to the effects of thermal and mechanical stresses,
and produces devices that have extremely stable quiescent Hall
output voltages and precise recoverability after temperature
cycling. This technique is made possible through the use of a
BiCMOS process, which allows the use of low-offset, low-noise
amplifiers in combination with high-density logic integration and
sample-and-hold circuits.
When using Hall-effect technology, a limiting factor for
switchpoint accuracy is the small signal voltage developed
across the Hall element. This voltage is disproportionally small
relative to the offset that can be produced at the output of the
Hall sensor. This makes it difficult to process the signal while
maintaining an accurate, reliable output over the specified oper-
ating temperature and voltage ranges.
Chopper stabilization is a unique approach used to minimize
Hall offset on the chip. The patented Allegro technique, namely
Dynamic Quadrature Offset Cancellation, removes key sources
of the output drift induced by thermal and mechanical stresses.
This offset reduction technique is based on a signal modulation-
demodulation process. The undesired offset signal is separated
from the magnetic-field-induced signal in the frequency domain,
through modulation. The subsequent demodulation acts as a
modulation process for the offset, causing the magnetic-field-
induced signal to recover its original spectrum at baseband,
while the dc offset becomes a high-frequency signal. The mag-
netic-field-induced signal then can pass through a low-pass filter,
while the modulated dc offset is suppressed. This configuration
is illustrated in figure 2.
The repeatability of magnetic-field-induced switching is affected
slightly by a chopper technique. However, the Allegro high-
frequency chopping approach minimizes the affect of jitter and
makes it imperceptible in most applications. Applications that
are more likely to be sensitive to such degradation are those
requiring precise sensing of alternating magnetic fields; for
example, speed sensing of ring-magnet targets. For such applica-
tions, Allegro recommends its digital sensor families with lower
sensitivity to jitter. For more information on those devices,
contact your Allegro sales representative.
Regulator
Clock/Logic
Hall Element
Amp
Figure 2. Chopper Stabilization Circuit (Dynamic Quadrature Offset Cancellation)
Allegro MicroSystems, Inc.
9
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Power Derating
Example: Reliability for VCC at TA=150°C, package LH, using a
The device must be operated below the maximum junction
temperature of the device, TJ(max). Under certain combinations of
peak conditions, reliable operation may require derating sup-
plied power or improving the heat dissipation properties of the
application. This section presents a procedure for correlating
factors affecting operating TJ. (Thermal data is also available on
the Allegro MicroSystems Web site.)
low-K PCB.
Observe the worst-case ratings for the device, specifically:
RθJA=228 °C/W, TJ(max) =165°C, VCC(max)= 24 V, and
ICC(max) = 5 mA.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
The Package Thermal Resistance, RθJA, is a figure of merit sum-
marizing the ability of the application and the device to dissipate
heat from the junction (die), through all paths to the ambient air.
Its primary component is the Effective Thermal Conductivity,
K, of the printed circuit board, including adjacent devices and
traces. Radiation from the die through the device case, RθJC, is
relatively small component of RθJA. Ambient air temperature,
TA, and air motion are significant external factors, damped by
overmolding.
ΔTmax = TJ(max) – TA = 165°C–150°C = 15°C
This provides the allowable increase to TJ resulting from internal
power dissipation. Then, invert equation 2:
PD(max) = ΔTmax ÷RθJA =15°C÷228 °C/W=65.8mW
Finally, invert equation 1 with respect to voltage:
V
CC(est) = PD(max) ÷ ICC(max) = 65.8mW÷5 mA=13.2 V
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤VCC(est)
The effect of varying power levels (Power Dissipation, PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD.
.
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reli-
able operation between VCC(est) and VCC(max) requires enhanced
RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and
VCC(max) is reliable under these conditions.
PD = VIN
I
(1)
(2)
(3)
×
IN
ΔT = PD
R
θJA
×
TJ = TA + ΔT
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 1.5 mA, and RθJA = 165 °C/W, then:
PD = VCC
I
= 12 V 1.5 mA = 18 mW
×
×
CC
ΔT = PD
R
= 18 mW 165 °C/W = 3°C
×
×
θJA
TJ = TA + ΔT = 25°C + 3°C = 28°C
A worst-case estimate, PD(max), represents the maximum allow-
able power level (VCC(max), ICC(max)), without exceeding TJ(max)
at a selected RθJA and TA.
,
Allegro MicroSystems, Inc.
10
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Package LH, 3-Pin (SOT-23W)
Package UA, 3-Pin
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
11
A3241-DS, Rev. 2
A3241 and A3242
Chopper-Stabilized Unipolar Hall Effect Switches
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 compo-
nents in life-support devices or systems without express written
approval.
The information included herein is believed to be accurate and
reliable. However, Allegro MicroSystems, Inc. assumes no respon-
sibility for its use; nor for any infringement of patents or other
rights of third parties which may result from its use.
Copyright © 2005 Allegro MicroSystems, Inc.
Allegro MicroSystems, Inc.
12
115 Northeast Cutoff, Box 15036
A3241-DS, Rev. 2
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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