Allegro A1142LUA Sensitive two-wire chopper-stabilized unipolar hall-effect switch Datasheet

A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall-Effect Switches
Package LH, 3-pin SOT
3
1. VCC
2. No connection
3. GND
NC
1
2
Package UA, 3-pin SIP
PTCT
1. VCC
2. GND
3. GND
1
2
3
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC .......................................... 28 V
Reverse-Supply Voltage, VRCC ........................ –18 V
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
The A1140, A1141, A1142, and A1143 devices are sensitive, two-wire, unipolar, Hall effect switches that are factory-programmed at end-of-line to optimize
magnetic switchpoint accuracy. These devices are produced on the Allegro
MicroSystems advanced BiCMOS wafer fabrication process, which implements a
patented, high-frequency, chopper-stabilization technique that achieves magnetic
stability and eliminates the offsets that are inherent in single-element devices
exposed to harsh application environments. Commonly found in a number of
automotive applications, the A1140-43 family of devices are utilized to sense: seat
track position, seat belt buckle presence, hood/trunk latching, and shift selector
position.
Two-wire unipolar switches are particularly advantageous in price-sensitive applications, because they require one less wire than the more traditional open-collector output switches. Additionally, the system designer gains inherent diagnostics
because output current normally flows in either of two narrowly-specified ranges.
Any output current level outside of these two ranges is a fault condition. The
A1140-43 family of devices also features on-chip transient protection, and a Zener
clamp to protect against overvoltage conditions on the supply line.
The output currents of the A1141 and A1143 switch HIGH in the presence of a south
polarity magnetic field of sufficient strength; and switch LOW otherwise, including
when there is no significant magnetic field present. The A1140 and A1142 have
inverted output current levels: switching LOW in the presence of a south polarity
magnetic field of sufficient strength, and HIGH otherwise. The devices also differ in
their specified LOW current supply levels.
All family members are offered in two package styles: SOT-23W, a miniature lowprofile package for surface-mount applications (suffix –LH), and TO-92, threelead ultra-mini Single Inline Package (SIP) for through-hole mounting
(suffix –UA).
Field-programmable versions are also available. Refer to: A1180, A1181, A1182,
and A1183.
Features and Benefits
Chopper stabilization
Low switchpoint drift over operating temperature range
Low stress sensitivity
Factory programmed at end-of-line for
optimized switchpoints
A1140-DS
On-chip protection
Supply transient protection
Reverse-battery protection
On-board voltage regulator
3.5 V to 24 V operation
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Functional Block Diagram
V+
VCC
Program/Lock
Programming
Logic
Offset
Regulator
Clock/Logic
Amp
Low-Pass
Filter
Sample and Hold
Dynamic Offset
Cancellation
0.01 uF
GND
GND
Package UA Only
Product Selection Guide
Use the complete part numbers when ordering
Part Number
Package
A1140ELH
Surface Mount
A1140EUA
SIP
A1140LLH
Surface Mount
A1140LUA
SIP
A1141ELH
Surface Mount
A1141EUA
SIP
A1141LLH
Surface Mount
A1141LUA
SIP
A1142ELH
Surface Mount
A1142EUA
SIP
A1142LLH
Surface Mount
A1142LUA
SIP
A1143ELH
Surface Mount
A1143EUA
SIP
A1143LLH
Surface Mount
A1143LUA
SIP
1South
TA
(ºC)
Output
Supply Current at
Low Output, ICC(L)
(mA)
South
(+) Field1
Other
Field2
2 to 5
Low
High
2 to 5
High
Low
5 to 6.9
Low
High
5 to 6.9
High
Low
–40 to 85
–40 to 150
–40 to 85
–40 to 150
–40 to 85
–40 to 150
–40 to 85
–40 to 150
(+) magnetic fields must be of sufficient strength.
north (–) magnetic fields of sufficient strength, and weak fields of either polarity.
2Includes
2
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
ELECTRICAL CHARACTERISTICS over the operating voltage and temperature range, unless otherwise specified
Characteristic
Supply Voltage
Supply Current1
Symbol
VCC
ICC(L)
ICC(H)
Zener Clamp Supply Voltage
VZ(supply)
Zener Clamp Supply Current2
IZ(supply)
Output Slew Rate3
Chopping Frequency
di/dt
Test Conditions
Min.
Typ.
Max.
Units
3.5
–
24
V
B >BOP for A1140; B <BRP for A1141
2
–
5
mA
B >BOP for A1142; B <BRP for A1143
5
–
6.9
mA
B >BOP for A1141, A1143
B <BRP for A1140, A1142
12
–
17
mA
ICC = ICC(max) + 3 mA; TA = 25°C
28
–
40
V
VZ(supply) = 28 V
–
–
10
mA
No bypass capacitor; capacitance of the
oscilloscope performing the measurement
= 20 pF
–
36
–
mA/µs
Device powered on
fC
Power-On Time4
ton
Power-On State5
POS
–
400
–
kHz
After factory programming; with and without
bypass capacitor (CBYP = 0.01 µF)
–
–
25
µs
ton ≤ ton(max); VCC slew rate ≥ 25 mV/µs
–
HIGH
–
–
1Relative
values of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic
polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present).
2The maximum value for I
Z(supply) is equal to ICC(L)MAX + 3 mA.
3The value of di is the difference between 90% of I
CC(H) and 10% of ICC(L), and the value of dt is time period between those two points. The value of di/dt
depends on the value of the bypass capacitor, if one is used, with greater capacitances resulting in lower rates of change.
4The value of t depends on the value of the bypass capacitor, if one is used, with greater capacitances resulting in longer t .
on
on
5A V slew rate less than 25 mV/µs affects device performance, both while powering-on and while running. For t > t
CC
on
on(max), and BRP < B < BOP, POS
is undefined.
MAGNETIC CHARACTERISTICS* over the operating voltage and temperature range, unless otherwise specified
Characteristic
Symbol
Operate Point
BOP
Release Point
BRP
Hysteresis
BHYS
Test Conditions
ICC(H) → ICC(L)
ICC(L) → ICC(H)
ICC(L) → ICC(H)
ICC(H) → ICC(L)
for A1140, A1142
for A1141, A1143
for A1140, A1142
for A1141, A1143
BHYS = BOP – BRP
Min.
Typ.
Max.
Units
50
85
115
G
45
–
110
G
5
15
30
G
*Relative values of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic
polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present).
3
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Characteristic Data
10
ICC(L) versus Ambient Temperature
at Various Levels of VCC
(A1140, A1141, A1142, A1143)
ICC(H) versus Ambient Temperature
at Various Levels of VCC
(A1140, A1141, A1142, A1143)
20
8
ICC(L) (mA)
6
3.8 V
12.0 V
24.0 V
4
2
0
ICC(H) (mA)
18
VCC
VCC
16
3.8 V
12.0 V
24.0 V
14
12
–40
25
10
150
–40
Ambient Temperature, TA (°C)
110
Switchpoint versus Ambient Temperature
(A1143)
30
25
150
Ambient Temperature, TA (°C)
Hysteresis versus Ambient Temperature
(A1143)
105
100
25
95
BHYS (G)
BOP (G)
90
85
80
75
20
15
70
10
65
60
55
–50
0
50
100
150
200
5
–50
0
Ambient Temperature, TA (°C)
50
100
150
200
Ambient Temperature, TA (°C)
Device Qualification Program
Contact Allegro MicroSystems for information.
EMC (Electromagnetic Compatibility) Requirements
Contact your local representative for EMC results.
Test Name
Reference Specification
ESD – Human Body Model
AEC-Q100-002
ESD – Machine Model
AEC-Q100-003
Conducted Transients
ISO 7637-1
Direct RF Injection
ISO 11452-7
Bulk Current Injection
ISO 11452-4
TEM Cell
ISO 11452-3
4
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions
Package LH, minimum-K PCB (single-sided with
copper limited to solder pads)
Package LH, low-K PCB (double-sided with
0.926 in2 copper area)
Package UA, minimum-K PCB (single-sided with
copper limited to solder pads)
RθJA
Maximum Allowable VCC (V)
Package Thermal Resistance
Typ.
Max Units
110
–
–
ºC/W
228
–
–
ºC/W
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)
Low-K PCB, Package LH
(RθJA = 110 ºC/W)
Minimum-K PCB, Package UA
(RθJA = 165 ºC/W)
Minimum-K PCB, Package LH
(RθJA = 228 ºC/W)
20
Power Dissipation, PD (m W)
Min.
40
60
80
100
120
VCC(min)
140
160
180
Maximum Power Dissipation, PD(max)
TJ(max) = 165ºC; VCC = VCC(max); ICC = ICC(max)
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
Lo
(R w-K
PC
θJ
A =
11 B, P
0 º ac
Min
C/ ka
W ge
(R imum
)
LH
KP
θJA =
165 CB
ºC/ , Pac
W)
kag
eU
A
Min
imu
m-K
(R
P
θJA =
228 CB, Pa
ºC/W
ckag
e LH
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
5
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Functional Description
Operation
The output, ICC, of the A1140 and A1142 devices switch low
after the magnetic field at the Hall sensor exceeds the operate point threshold, BOP. When the magnetic field is reduced to
below the release point threshold, BRP, the device output goes
high. The differences between the magnetic operate and release
point is called the hysteresis of the device, BHYS. This built-
I+
in hysteresis allows clean switching of the output even in the
presence of external mechanical vibration and electrical noise.
The A1141 and A1143 devices switch with opposite polarity for
similar BOP and BRP values, in comparison to the A1140 and
A1142 (see figure 1).
I+
Switch to High
ICC
ICC
ICC(H)
Switch to Low
Switch to Low
Switch to High
ICC(H)
ICC(L)
BRP
BHYS
(A) A1140, A1142
B+
B–
BRP
BOP
B–
ICC(L)
0
BOP
0
B+
BHYS
(B) A1141, A1143
Figure 1. Alternative switching behaviors are available in the A114x device family. 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).
6
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Chopper Stabilization Technique
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 operating 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 modulationdemodulation 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 fieldinduced signal to recover its original spectrum at baseband, while
the dc offset becomes a high-frequency signal. The magneticsourced signal then can pass through a low-pass filter, while the
modulated dc offset is suppressed.
The chopper stabilization technique uses a 200 kHz high frequency clock. The chopping occurs on each clock edge, result-
ing in a 400 kHz chop frequency. This high-frequency operation allows a greater sampling rate, which results in higher
accuracy and faster signal-processing capability. This approach
desensitizes 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. This process 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 applications, Allegro recommends its digital sensor families with lower sensitivity to jitter. For more information on
those devices, contact your Allegro sales representative.
Regulator
Hall Element
Amp
Sample and
Hold
Clock/Logic
Low-Pass
Filter
Figure 2. Chopper stabilization circuit (dynamic quadrature offset cancellation)
7
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Application Information
For additional general application information, visit the Allegro
MicroSystems Web site at www. allegromicro.com.
Typical Application Circuit
The A114x family of devices must be protected by an external
bypass capacitor, CBYP, connected between the supply, VCC,
and the ground, GND, of the device. CBYP reduces both external
noise and the noise generated by the chopper-stabilization function. As shown in figure 3, a 0.01 µF capacitor is typical.
V+
VCC
A114x
Installation of CBYP must ensure that the traces that connect it to
the A114x pins are no greater than 5 mm in length.
All high-frequency interferences conducted along the supply
lines are passed directly to the load through CBYP, and it serves
only to protect the A114x internal circuitry. As a result, the load
ECU (electronic control unit) must have sufficient protection,
other than CBYP, installed in parallel with the A114x.
A series resistor on the supply side, RS (not shown), in combination with CBYP, creates a filter for EMI pulses. (Additional
information on EMC is provided on the Allegro MicroSystems
Web site.)
When determining the minimum VCC requirement of the A114x
device, the voltage drops across RS and the ECU sense resistor,
RSENSE, must be taken into consideration. The typical value for
RSENSE is approximately 100 Ω.
B
GND
CBYP
0.01 uF
GND
B
A
A
Package UA Only
B
Maximum separation 5 mm
RSENSE
ECU
Figure 3. Typical application circuit
8
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Power Derating
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 supplied 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.)
The Package Thermal Resistance, RθJA, is a figure of merit summarizing 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.
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.
PD = VIN × IIN
(1)
∆T = PD × RθJA
(2)
TJ = TA + ∆T
(3)
Example: Reliability for VCC at TA = 150°C, package UA, using
minimum-K PCB.
Observe the worst-case ratings for the device, specifically:
RθJA = 165°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and
ICC(max) = 17 mA.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
∆Tmax = 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) = ∆Tmax ÷ RθJA = 15°C ÷ 165 °C/W = 91 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 17 mA = 5 V
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤VCC(est).
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reliable 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.
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 4 mA, and RθJA = 140 °C/W, then:
PD = VCC × ICC = 12 V × 4 mA = 48 mW
∆T = PD × RθJA = 48 mW × 140 °C/W = 7°C
TJ = TA + ∆T = 25°C + 7°C = 32°C
A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max),
at a selected RθJA and TA.
9
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Package LH, 3-Pin; (SOT-23W)
3.10 .122
2.90 .114
1.49 .059
NOM
3
8º
0º
0.28 .011
NOM
0.70 .028
BSC
0.20 .008
0.13 .005
C
0.96 .038
NOM
2.10 .083
1.85 .073
2.40 .094
BSC
A
0.25 .010
MIN
3.00 .118
2.70 .106
1.00 .039
BSC
1
2
0.95 .037
BSC
0.25 .010
BSC
Seating Plane
Gauge Plane
0.50 .020
0.30 .012
1.13 .045
0.87 .034
0.55 .022
REF
A
Dimensions in millimeters
U.S. Customary dimensions (in.) in brackets, for reference only
Hall element
B
Active Area Depth 0.28 [.011]
C
Fits SC–59A Solder Pad Layout
0.15 .006
0.00 .000
0.95 .037
BSC
Package UA, 3-Pin; (TO-92)
.164 4.17
.159 4.04
45°
BSC
.0195 0.50
NOM
.0805 2.04
NOM
.122 3.10
.117 2.97
.062 1.57
.058 1.47
.0565 1.44
NOM
45°
BSC
B
.085 2.16
MAX
.640 16.26
.600 15.24
.031 0.79
REF
A
1
2
3
.017 0.44
.014 0.35
.019 0.48
.014 0.36
.050 1.27
BSC
Dimensions in inches
Metric dimensions (mm) in brackets, for reference only
A Dambar removal protrusion
B Hall element
10
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1140/41/42/43
Sensitive Two-Wire 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 components 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 responsibility for its use; nor for any infringement of patents or other
rights of third parties which may result from its use.
Copyright © 2004 Allegro MicroSystems, Inc.
11
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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