A1126 Datasheet

A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Description
Features and Benefits
•AEC-Q100 automotive qualified
•Omnipolar operation
•Low switchpoint drift
•Superior temperature stability
•Insensitive to physical stress
•Reverse-battery protection
•Robust EMC capability
•Robust ESD protection
The A1126 integrated circuit is an omnipolar, ultrasensitive
Hall-effect switch with a digital output. This device has an
integrated regulator permitting operation to 24 V.
This device is especially suited for operation through extended
temperature ranges, up to 150°C. Superior high-temperature
performance is made possible through an Allegro™ patented
dynamic offset cancellation, which reduces the residual offset
voltage normally caused by device overmolding, temperature
excursions, and thermal stress.
Packages:
3-pin SOT23-W
2 mm × 3 mm × 1 mm
(suffix LH)
3-pin ultramini SIP
1.5 mm × 4 mm × 3 mm
(suffix UA)
Not to scale
The A1126 Hall-effect switch includes 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.
The omnipolar operation of the A1126 allows activation with
either a north or a south polarity field of sufficient strength. In
the absence of a magnetic field, the output is off. This patented
magnetic-polarity-independence feature makes this device
an excellent replacement for reed switches, with improved
ease of manufacturing, because the A1126 does not require
Continued on the next page…
Approximate footprint
Functional Block Diagram
VOUT
VCC
Dynamic Offset Cancellation
Regulator
To all subcircuits
Omnipolar
Switchpoints
Amplifier
Signal
Recovery
Control
Current
Limit
GND
A1126-DS, Rev. 2
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Description (continued)
manufacturers to orient their magnets. These devices allow simple
on/off switching in industrial, consumer, and automotive applications.
a miniature low-profile surface-mount package, while package
UA is a three-lead ultra-mini SIP for through-hole mounting. Each
package is lead (Pb) free, with 100% matte-tin-plated leadframe.
The A1126 is rated for operation between the ambient temperatures
–40°C to 150°C. The available package styles provide magnetically
optimized solutions for most applications. Package LH is an SOT23W,
Selection Guide
Part Number
Packing1
Package
A1126LLHLT-T2
3,000 pieces per reel
3-pin SOT-23W surface mount
A1126LLHLX-T
10,000 pieces per reel
3-pin SOT-23W surface mount
A1126LUA-T
500 pieces per bag
3-pin ultramini SIP through-hole mount
1 Contact Allegro™
for additional packing options
2 Available through authorized Allegro distributors only.
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Unit
Forward Supply Voltage
VCC
28
V
Reverse Supply Voltage
VRCC
–18
V
Output Off Voltage
VOUT
28
V
Reverse Supply Current
IRCC
–2
mA
Continuous Output Current
IOUT
Internally limited
–
–40 to 150
ºC
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Operating Ambient Temperature
TA
Maximum Junction Temperature
Storage Temperature
L temperature range
Pin-Out Diagrams
Terminal List Table
3
Name
1
2
LH Package
3-Pin SOT23W
1
2
Number
Function
LH
UA
VCC
1
1
Connects power supply to chip
VOUT
2
3
Output from circuit
GND
3
2
Ground
3
UA Package
3-Pin SIP
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
OPERATING CHARACTERISTICS: Valid through TA and VCC ranges, TJ < TJ(max), CBYP = 0.1 µF, unless otherwise specified
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Unit1
Electrical Characteristics
Supply Voltage
Output Leakage Current
Output On Voltage
VCC
Operating, TJ < 165°C
3
–
24
V
IOUTOFF
VOUT = 24 V, B < BRPS
–
–
10
µA
VOUT(SAT)
IOUT = 20 mA, B > BOP
–
185
500
mV
B > BOP
30
–
60
mA
–
–
25
µs
Output Current Limit
IOM
Power-On Time2,3
tPO
Chopping Frequency
fC
–
800
–
kHz
Output Rise Time3,4
tr
RLOAD = 820 Ω, CS = 20 pF
–
0.2
2
µs
tf
RLOAD = 820 Ω, CS = 20 pF
–
0.1
2
µs
B > BOP , VCC = 12 V
–
–
4
mA
Output Fall
Time3,4
Supply Current
Supply Zener Clamp Voltage
Supply Zener Current
ICC(ON)
ICC(OFF)
VZ
IZSUPPLY
B < BRP , VCC = 12 V
–
–
4
mA
ICC = 6.5 mA; TA = 25°C
28
–
–
V
VS = 28 V
–
–
6.5
mA
Magnetic Characteristics
Operate Point
Release Point
Hysteresis
BOPS
South pole adjacent to branded face
15
38
55
G
BOPN
North pole adjacent to branded face
-55
-38
-15
G
BRPS
South pole adjacent to branded face
5
20
50
G
BRPN
North pole adjacent to branded face
-50
-20
-5
G
BHYS
| BOPS – BRPS |, | BOPN – BRPN |
5
–
30
G
11
G (gauss) = 0.1 mT (millitesla).
< BRP (min) – 10 G , B > BOP (max) + 10 G.
3 Guaranteed by device design and characterization.
4 C = oscilloscope probe capacitance.
S
2B
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Characteristic Performance
Average Supply Current (On) versus Temperature
Average Supply Current (On) versus Supply Voltage
4.0
Supply Current, ICC(ON) (mA)
Supply Current, ICC(ON) (mA)
4.0
3.5
VCC = 24 V
3.0
2.5
VCC = 3.0 V
2.0
1.5
1.0
0.5
0
-60
-40
-20
0
20
40
60
80
100
120
140
3.5
2.5
TA = 25°C
2.0
1.5
1.0
0.5
0
160
0
5
Average Supply Current (Off) versus Temperature
15
20
25
Average Supply Current (Off) versus Supply Voltage
4.0
Supply Current, ICC(OFF) (mA)
4.0
Supply Current, ICC(OFF) (mA)
10
Supply Voltage, VCC (V)
Ambient Temperature, TA (°C)
3.5
3.0
VCC = 24 V
2.5
2.0
VCC = 3.0 V
1.5
1.0
0.5
0
-60
TA = 150°C
TA = –40°C
3.0
-40
-20
0
20
40
60
80
100
Ambient Temperature, TA (°C)
120
140
160
3.5
3.0
TA = 150°C
TA = –40°C
2.5
2.0
TA = 25°C
1.5
1.0
0.5
0
0
5
10
15
20
25
Supply Voltage, VCC (V)
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Average Operate Point (South) versus Supply Voltage
55
55
50
50
Operate Point (BOP)
Applied Flux Density (G)
Operate Point (BOP)
Applied Flux Density (G)
Average Operate Point (South) versus Temperature
45
40
35
VCC = 3.0 V
30
VCC = 24 V
25
20
15
-60
-40
-20
0
20
40
60
80
100
120
140
45
40
TA = 25°C
25
20
0
5
50
50
45
45
40
35
30
VCC = 3.0 V
15
VCC = 24 V
10
5
-60
-40
-20
0
20
40
60
80
100
Ambient Temperature, TA (°C)
15
20
25
Average Release Point (South) versus Supply Voltage
Release Point (BRP)
Applied Flux Density (G)
Release Point (BRP)
Applied Flux Density (G)
Average Release Point (South) versus Temperature
20
10
Supply Voltage, VCC (V)
Ambient Temperature, TA (°C)
25
TA = 150°C
30
15
160
TA = –40°C
35
120
140
160
40
35
30
25
TA = 150°C
TA = –40°C
20
15
TA = 25°C
10
5
0
5
10
15
20
25
Supply Voltage, VCC (V)
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Average Operate Point (North) versus Supply Voltage
–15
–15
–20
–20
Operate Point (BOP)
Applied Flux Density (G)
Operate Point (BOP)
Applied Flux Density (G)
Average Operate Point (North) versus Temperature
–25
–30
VCC = 24 V
–35
VCC = 3.0 V
–40
–45
–50
–55
-60
-40
-20
0
20
40
60
80
100
120
140
–25
–35
–45
–50
0
5
–5
–5
–10
–10
VCC = 24 V
–20
VCC = 3.0 V
–30
–35
–40
–45
–50
-60
-40
-20
0
20
40
60
80
100
Ambient Temperature, TA (°C)
15
20
25
Average Release Point (North) versus Supply Voltage
Release Point (BRP)
Applied Flux Density (G)
Release Point (BRP)
Applied Flux Density (G)
Average Release Point (North) versus Temperature
–25
10
Supply Voltage, VCC (V)
Ambient Temperature, TA (°C)
–15
TA = 150°C
TA = –40°C
–40
–55
160
TA = 25°C
–30
120
140
160
TA = –40°C
–15
–20
TA = 25°C
–25
TA = 150°C
–30
–35
–40
–45
–50
0
5
10
15
20
25
Supply Voltage, VCC (V)
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Average Hysteresis (South) versus Supply Voltage
Average Hysteresis (South) versus Temperature
30
Switchpoint Hysteresis (BHYS)
Applied Flux Density (G)
Switchpoint Hysteresis (BHYS)
Applied Flux Density (G)
30
25
20
15
VCC = 3.0 V
VCC = 24 V
10
5
-60
-40
-20
0
20
40
60
80
100
120
140
25
20
TA = –40°C
15
10
TA = 150°C
5
0
160
5
15
20
25
Average Hysteresis (North) versus Supply Voltage
Average Hysteresis (North) versus Temperature
30
Switchpoint Hysteresis (BHYS)
Applied Flux Density (G)
30
25
20
15
VCC = 24 V
VCC = 3.0 V
10
-40
-20
0
20
40
60
80
100
120
140
25
20
TA = –40°C
15
TA = 25°C
10
TA = 150°C
5
0
160
5
Ambient Temperature, TA (°C)
10
15
20
25
Supply Voltage, VCC (V)
Average Output Saturation Voltage versus Temperature
IOUT = 20 mA, VCC = 12 V, B > BOP
500
Output Saturation Voltage
VOUT(SAT), (mV)
Switchpoint Hysteresis (BHYS)
Applied Flux Density (G)
10
Supply Voltage, VCC (V)
Ambient Temperature, TA (°C)
5
-60
TA = 25°C
450
400
350
300
250
200
150
100
50
0
-60
-40
-20
0
20
40
60
80
100
120
140
160
Ambient Temperature, TA (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
THERMAL CHARACTERISTICS: may require derating at maximum conditions; see application information
Characteristic
Symbol
RθJA
Package Thermal Resistance
Test Conditions*
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
*Additional thermal information available on Allegro Web site.
Maximum Allowable VCC (V)
Power Derating Curve
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)
2-layer PCB, Package LH
(RθJA = 110 ºC/W)
1-layer PCB, Package UA
(RθJA = 165 ºC/W)
1-layer PCB, Package LH
(RθJA = 228 ºC/W)
20
40
60
80
100
120
VCC(min)
140
160
180
Temperature (ºC)
Power Dissipation, PD (m W)
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
2l
(R aye
rP
θJ
C
A =
11 B, P
0 º ac
1-la
C/ ka
y
W
(R er PC
) ge L
θJA =
B
H
165 , Pac
k
ºC/
a
W) ge U
A
1-lay
er P
(R
CB,
θJA =
228 Packag
ºC/W
e LH
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Functional Description
The output of these devices switches low (turns on) when a
magnetic field perpendicular to the Hall sensor chip exceeds the
operate point threshold, BOPx . 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, BRPx , 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 switch-
ing of the output even in the presence of external mechanical
vibration and electrical noise.
In the case of omnipolar switch devices, removal of the magnetic
field results in the device output high (off).
Powering-on the device in the hysteresis range (less than BOPx
and greater than BRPx ) will allow an indeterminate output state.
The correct state is attained after the first excursion beyond BOPx
or BRPx .
V+
Switch to High
VOUT
VOUT(SAT)
BHYS
BRPS
0
BOPS
BOPN
B–
BRPN
0
Switch to Low
Switch to Low
Switch to High
VS
B+
BHYS
Figure 1. Switching behavior of omnipolar switches. On the horizontal axis, the
B+ direction indicates increasing south polarity magnetic field strength, and the
B– direction indicates increasing north polarity. This behavior can be exhibited
when using a circuit such as that shown in figure 2.
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115 Northeast Cutoff
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A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Application Information
V+
VCC
RLOAD
A1126
CBYPASS
0.1 µF
VOUT
GND
Figure 2. Typical Application Circuit
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
chip. 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 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 spec-
trum at baseband, while the DC offset becomes a high-frequency
signal. The magnetic-sourced signal then can pass through a
low-pass filter, while the modulated DC offset is suppressed. The
chopper stabilization technique uses a 400 kHz high frequency
clock. For demodulation process, a sample-and-hold technique is
used, where the sampling is performed at twice the chopper 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 highdensity logic integration and sample-and-hold circuits.
Regulator
Hall Element
Amp
Sample and
Hold
Clock/Logic
Low-Pass
Filter
Figure 3. Concept of Chopper Stabilization Technique
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115 Northeast Cutoff
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A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
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)
ΔT = PD × RθJA(2)
TJ = TA + ΔT
(3)
Example: Reliability for VCC at TA = 150°C, package UA, using a
single-layer 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) = 4 mA.
Calculate the maximum allowable power level, PD(max) . First,
invert equation 3:
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 ÷ 165 °C/W = 91 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 4 mA = 23 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,
VIN = 12 V, IIN = 4 mA, and RθJA = 140 °C/W, then:
PD = VIN × IIN = 12 V × 4 mA = 48 mW
ΔT = PD × RθJA = 48 mW × 140 °C/W = 7°C
TJ = TA + ΔT = 25°C + 7°C = 32°C
A worst-case estimate, PD(max) , represents the maximum allowable power level, without exceeding TJ(max) , at a selected RθJA
and TA.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Package LH, 3-Pin SOT23W
+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
8X 10° REF
B
PCB Layout Reference View
Branded Face
1.00 ±0.13
0.95 BSC
+0.10
0.05 –0.05
0.40 ±0.10
NNN
1
C
Standard Branding Reference View
N = Last three digits of device part number
For Reference Only; not for tooling use (reference DWG-2840)
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
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Package UA, 3-Pin SIP
+0.08
4.09 –0.05
45°
B
E
C
2.04
1.52 ±0.05
+0.08
3.02 –0.05
1.44
E
10°
Mold Ejector
Pin Indent
E
Branded
Face
A
1.02
MAX
45°
0.79 REF
NNN
1
1
2
D Standard Branding Reference View
3
= Supplier emblem
N = Last three digits of device part number
+0.03
0.41 –0.06
14.99 ±0.25
+0.05
0.43 –0.07
For Reference Only; not for tooling use (reference DWG-9065)
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 and tie bar burr area
C
Active Area Depth, 0.50 mm REF
D
Branding scale and appearance at supplier discretion
E
Hall element (not to scale)
1.27 NOM
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
A1126
Chopper-Stabilized Omnipolar Hall-Effect Switch
Revision History
Revision
Revision Date
1
September 16, 2013
Update UA package drawing
Description of Revision
2
September 21, 2015
Added AEC-Q100 qualification under Features and
Benefits
Copyright ©2015, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC 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 any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC 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, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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