A1120, A1121, A1122, A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
FEATURES AND BENEFITS
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DESCRIPTION
AEC-Q100 automotive qualified
Unipolar switchpoints
Resistant to physical stress
Superior temperature stability
Output short-circuit protection
Operation from unregulated supply
Reverse-battery protection
Solid-state reliability
Small package sizes
The A1120, A1121, A1122, A1123, and A1125 Hall-effect
unipolar switches are extremely temperature-stable and
stress-resistant sensor ICs, especially suited for operation
over extended temperature ranges to 150°C. Superior hightemperature performance is made possible through dynamic
offset cancellation, which reduces the residual offset voltage
normally caused by device overmolding, temperature
dependencies, and thermal stress.
Each 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-drain output to sink up to 25 mA.
PACKAGES:
Not to scale
NOT FOR
NEW DESIGN
3-pin SOT23W
(suffix LH)
3-pin SIP,
matrix HD style
(suffix UA)
3-pin SIP,
chopper style
(suffix UA)
An on-board regulator permits operation with supply voltages
of 3 to 24 V. The advantage of operating down to 3 V is that
the device can be used in 3 V applications or with additional
external resistance in series with the supply pin for greater
protection against high-voltage transient events.
For the A1120, A1121, A1122, and A1123, a south pole of
sufficient strength turns the output on. Removal of the magnetic
field turns the output off. The A1125 is complementary, in that
for these devices, a south pole turns the A1125 output off, and
removal of the magnetic field turns the output on.
Two package styles provide a magnetically optimized package
for most applications. Package type LH is a modified SOT23W,
surface-mount package, while UA is a three-lead ultra-mini
SIP for through-hole mounting. Each package type is lead
(Pb) free (suffix, –T), with a 100% matte-tin-plated leadframe.
Functional Block Diagram
VCC
Amp
Sample and Hold
Dynamic Offset
Cancellation
Regulator
Low-Pass
Filter
To All Subcircuits
VOUT
Control
Current Limit
GND
A1120-DS, Rev. 17
November 4, 2016
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
SELECTION GUIDE
Part Number
Packing [1]
Mounting
A1120ELHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1120ELHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1120EUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1120LLHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1120LLHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1120LUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1121ELHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1121ELHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1121EUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1121LLHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1121LLHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1121LUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1122ELHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1122ELHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1122EUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1122LLHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1122LLHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1122LUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1123LLHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1123LLHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1123LUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1125ELHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1125ELHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1125EUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
A1125LLHLX-T
13-in. reel, 10000 pieces/reel
3-pin SOT23W surface mount
A1125LLHLT-T [2]
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1125LUA-T [3]
Bulk, 500 pieces/bag
3-pin SIP through hole
Ambient, TA
(°C)
Switchpoints
(Typ.) (G)
BOP
BRP
35
25
95
70
Output In South (Positive)
Magnetic Field
–40 to 85
–40 to 150
–40 to 85
On (logic low)
–40 to 150
–40 to 85
150
125
280
225
35
25
–40 to 150
–40 to 150
–40 to 85
Off (logic high)
–40 to 150
1 Contact Allegro
for additional packing options.
2 Available through authorized Allegro distributors only.
3 The chopper-style UA package is not for new design; the matrix HD style UA package is recommended for new designs.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
ABSOLUTE MAXIMUM RATINGS
Rating
Units
Forward Supply Voltage
Characteristic
Symbol
VCC
Notes
26.5
V
Reverse Supply Voltage
VRCC
–30
V
Output Off Voltage
VOUT
26
V
Continuous Output Current
IOUT
25
mA
Reverse Output Current
IROUT
–50
mA
Range E
–40 to 85
°C
Range L
–40 to 150
°C
TJ(max)
165
°C
Tstg
–65 to 170
°C
Operating Ambient Temperature
TA
Maximum Junction Temperature
Storage Temperature
GND
PINOUT DIAGRAMS AND TERMINAL LIST TABLE
3
2
3
VOUT
1
GND
2
VCC
1
VOUT
Package UA
VCC
Package LH
Terminal List
Name
Description
Number
Package LH
Package UA
Connects power supply to chip
1
1
VOUT
Output from circuit
2
3
GND
Ground
3
2
VCC
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
ELECTRICAL CHARACTERISTICS: Valid over full operating voltage and ambient temperature ranges, unless otherwise noted
Characteristics
Symbol
Test Conditions
Min.
Typ. [1]
Max.
Unit [2]
3
–
24
V
ELECTRICAL CHARACTERISTICS
Forward Supply Voltage
Output Leakage Current
Output Saturation Voltage
Output Current Limit
VCC
IOUTOFF
VOUT(SAT)
IOM
Power-On Time [3]
tPO
Operating, TJ < 165°C
A1120
A1121
A1122
A1123
VOUT = 24 V, B < BRP
–
–
10
µA
A1125
VOUT = 24 V, B > BOP
–
–
10
µA
A1120
A1121
A1122
A1123
IOUT = 20 mA, B > BOP
–
185
500
mV
A1125
IOUT = 20 mA, B < BRP
–
185
500
mV
A1120
A1121
A1122
A1123
B > BOP
30
–
60
mA
A1125
B < BRP
30
–
60
mA
–
–
25
µs
VCC > 3.0 V, B < BRP(min) – 10 G,
B > BOP(max) + 10 G
Chopping Frequency
fC
–
800
–
kHz
Output Rise Time [3][4]
tr
RL = 820 Ω, CS = 20 pF
–
0.2
2
µs
Output Fall Time [3][4]
tf
RL = 820 Ω, CS = 20 pF
–
0.1
2
µs
ICC(ON)
Supply Current
ICC(OFF)
Reverse Supply Current
IRCC
A1120
A1121
A1122
A1123
VCC = 12 V, B > BOP
–
–
4
mA
A1125
VCC = 12 V, B < BRP
–
–
4
mA
A1120
A1121
A1122
A1123
VCC = 12 V, B < BRP
–
–
4
mA
A1125
VCC = 12 V, B > BOP
–
–
4
mA
VRCC = –30 V
–
–
–5
mA
Supply Zener Clamp Voltage
VZ
ICC = 5 mA; TA = 25°C
28
–
–
V
Zener Impedance
IZ
ICC = 5 mA; TA = 25°C
–
50
–
Ω
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
ELECTRICAL CHARACTERISTICS (continued): Valid over full operating voltage and ambient temperature ranges,
unless otherwise noted
Characteristics
Symbol
Test Conditions
Max.
Unit [2]
Min.
Typ. [1]
A1120
–
35
50
G
A1121
50
95
135
G
A1122
120
150
200
G
A1123
205
280
355
G
A1125
–
35
50
G
A1120
5
25
–
G
A1121
40
70
110
G
MAGNETIC CHARACTERISTICS
Operate Point
Release Point
BOP
BRP
A1122
110
125
190
G
A1123
150
225
300
G
A1125
5
25
–
G
A1120
–
10
–
G
10
25
42
G
10
25
42
G
A1123
30
55
80
G
A1125
–
10
–
G
A1121
Hysteresis
BHYS
A1122
(BOP – BRP)
1 Typical
data are are at TA = 25°C and VCC = 12 V, and are for initial design estimations only.
G (gauss) = 0.1 mT (millitesla).
3 Guaranteed by device design and characterization.
4 C = oscilloscope probe capacitance.
S
21
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
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 LH, 2-layer PCB with 0.463
connected by thermal vias
RθJA
Package Thermal Resistance
in.2
of copper area each side
Maximum Allowable VCC (V)
Package UA, 1-layer PCB with copper limited to solder pads
Value
Units
228
°C/W
110
°C/W
165
°C/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
(RθJA = 110 ºC/W)
Package UA, 1-layer PCB
(RθJA = 165 ºC/W)
Package LH, 1-layer PCB
(RθJA = 228 ºC/W)
VCC(min)
20
40
60
80
100
120
140
160
180
Power Dissipation, PD (mW)
Temperature (ºC)
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
θJ
A =
L
11 H, 2
0 º -la
Pac
C/ ye
W
(R kage
) r PC
UA
θJA =
B
165 , 1-la
y
ºC/
W) er PC
B
Pac
k
(R age LH
,
θJA =
228 1-laye
ºC/W r PC
B
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
Characteristic Performance
A1120, A1121, A1122, A1123, and A1125 Electrical Characteristics
Average Supply Current (On) versus Ambient Temperature
Average Supply Current (On) versus Average Supply Voltage
6.0
6.0
5.5
5.5
5.0
5.0
4.5
4.0
VCC (V)
3.5
2.5
3.0
12
24
2.0
A112x*
1.5
A1123
3.0
1.0
ICC(av) (mA)
ICC(av) (mA)
4.5
–40
25
150
A112x*
3.0
2.5
2.0
A1123
1.0
*A1120, A1121,
A1122, and A1125
0.5
0
0
- 60
3.5
1.5
*A1120, A1121,
A1122, and A1125
0.5
TA (°C)
4.0
- 40
- 20
0
20
40
60
80
2
100 120 140 160
6
10
TA (°C)
Average Supply Current (Off) versus Ambient Temperature
6.0
5.5
5.0
5.0
VCC (V)
4.0
3.5
2.5
3.0
12
24
2.0
A112x*
1.5
A1123
3.0
1.0
ICC(av) (mA)
ICC(av) (mA)
26
4.5
4.5
TA (°C)
4.0
3.5
–40
25
150
A112x*
3.0
2.5
2.0
A1123
1.5
1.0
*A1120, A1121,
A1122, and A1125
0.5
*A1120, A1121,
A1122, and A1125
0.5
0
0
- 40
- 20
0
20
40
60
80
2
100 120 140 160
6
10
TA (°C)
14
18
22
26
VCC (V)
Average Output Saturation Voltage versus Supply Voltage
Average Output Saturation Voltage versus Ambient Temperature
300
300
250
250
VCC (V)
3.0
3.8
4.2
12
24
200
150
100
A112x*
A1123
50
*A1120, A1121,
A1122, and A1125
0
- 40
- 20
0
20
40
60
TA (°C)
80
100 120 140 160
VOUT(sat) (V)
VOUT(sat) (V)
22
Average Supply Current (Off) versus Average Supply Voltage
5.5
- 60
18
VCC (V)
6.0
- 60
14
200
TA (°C)
–40
25
150
A112x*
150
100
A1123
50
*A1120, A1121,
A1122, and A1125
0
2
6
10
14
18
22
26
VCC (V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
A1120 and A1125 Magnetic Characteristics
Average Operate Point versus Ambient Temperature
50
50
45
45
40
40
VCC (V)
30
3.0
25
24
20
35
BOP (G)
35
BOP (G)
Average Operate Point versus Average Supply Voltage
–40
25
25
150
20
15
15
10
10
5
5
0
TA (°C)
30
0
-60
-40
-20
0
20
40
60
80
100 120 140 160
2
6
10
TA (°C)
22
26
Average Release Point versus Average Supply Voltage
50
50
45
45
40
40
35
35
30
VCC (V)
25
3.0
20
BRP (G)
BRP (G)
18
VCC (V)
Average Release Point versus Ambient Temperature
24
15
30
TA (°C)
25
–40
20
25
15
150
10
10
5
5
0
0
-60 -40 -20
0
20
40
60
80
2
100 120 140 160
6
10
TA (°C)
14
18
22
26
VCC (V)
Average Switchpoint Hysteresis versus Supply Voltage
Average Switchpoint Hysteresis versus Ambient Temperature
20
20
18
18
16
16
14
12
VCC (V)
10
3.0
8
24
BHYS (G)
BHYS (G)
14
14
12
TA (°C)
10
–40
25
8
6
6
4
4
2
2
150
0
0
-60
-40
-20
0
20
40
60
TA (°C)
80
100 120 140 160
2
6
10
14
18
22
26
VCC (V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
A1121 Magnetic Characteristics
Average Operate Point versus Average Supply Voltage
140
140
130
130
120
120
110
VCC (V)
100
3.0
12
24
90
80
BOP (G)
BOP (G)
Average Operate Point versus Ambient Temperature
110
TA (°C)
100
–40
25
90
150
80
70
70
60
60
50
- 60 - 40 - 20
50
0
20
40
60
80
100 120 140 160
2
6
10
TA (°C)
110
100
100
90
90
80
VCC (V)
70
3.0
12
24
BRP (G)
BRP (G)
22
26
Average Release Point versus Average Supply Voltage
110
60
TA (°C)
80
–40
70
25
150
60
50
50
- 60 - 40 - 20
0
20
40
60
80
40
100 120 140 160
2
6
10
TA (°C)
18
22
26
Average Switchpoint Hysteresis versus Supply Voltage
40
35
35
30
VCC (V)
3.0
12
24
25
20
15
BHYS (G)
40
10
- 60 - 40 - 20
14
VCC (V)
Average Switchpoint Hysteresis versus Ambient Temperature
BHYS (G)
18
VCC (V)
Average Release Point versus Ambient Temperature
40
14
30
TA (°C)
25
–40
20
150
25
15
0
20
40
60
TA (°C)
80
100 120 140 160
10
2
6
10
14
18
22
26
VCC (V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
A1122 Magnetic Characteristics
Average Operate Point versus Ambient Temperature
Average Operate Point versus Average Supply Voltage
200
200
190
190
180
VCC (V)
170
3.0
12
24
160
150
BOP (G)
BOP (G)
180
–40
160
25
150
150
140
140
130
130
120
- 60 - 40 - 20
TA (°C)
170
120
0
20
40
60
80
100 120 140 160
2
6
10
TA (°C)
180
170
170
160
VCC (V)
150
3.0
12
24
140
BRP (G)
BRP (G)
190
180
TA (°C)
150
–40
130
120
60
80
25
140
120
40
110
100 120 140 160
150
2
6
10
TA (°C)
18
22
26
Average Switchpoint Hysteresis versus Supply Voltage
40
40
35
35
30
VCC (V)
3.0
12
24
25
20
BHYS (G)
BHYS (G)
14
VCC (V)
Average Switchpoint Hysteresis versus Ambient Temperature
30
TA (°C)
25
–40
20
150
25
15
15
10
- 60 - 40 - 20
26
160
130
20
22
Average Release Point versus Average Supply Voltage
190
0
18
VCC (V)
Average Release Point versus Ambient Temperature
110
- 60 - 40 - 20
14
0
20
40
60
TA (°C)
80
100 120 140 160
10
2
6
10
14
18
22
26
VCC (V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
A1123 Magnetic Characteristics
Average Operate Point versus Ambient Temperature
355
355
350
350
TA (°C)
3
280
12
24
255
TA (°C)
305
BOP (G)
305
BOP (G)
Average Operate Point versus Average Supply Voltage
–40
280
25
150
255
230
230
205
205
-60
-40
-20
0
20
40
60
80
100 120 140 160
2
6
10
TA (°C)
22
26
Average Release Point versus Average Supply Voltage
300
300
275
275
250
TA (°C)
225
3
12
200
BRP (G)
BRP (G)
18
VCC (V)
Average Release Point versus Ambient Temperature
24
175
250
TA (°C)
225
–40
200
150
25
175
150
150
-60 -40 -20
0
20
40
60
80
2
100 120 140 160
6
10
TA (°C)
14
18
22
26
VCC (V)
Average Switchpoint Hysteresis versus Supply Voltage
Average Switchpoint Hysteresis versus Ambient Temperature
80
80
75
75
70
70
65
65
60
TA (°C)
55
3
12
50
24
45
BHYS (G)
BHYS (G)
14
60
TA (°C)
55
–40
150
45
40
40
35
35
30
25
50
30
-60
-40
-20
0
20
40
60
TA (°C)
80
100 120 140 160
2
6
10
14
18
22
26
VCC (V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
Functional Description
Operation
The output of the A1120, A1121, A1122, and A1123 devices
switches low (turns on) when a magnetic field perpendicular to
the Hall element exceeds the operate point threshold, BOP (see
panel A of figure 1). When the magnetic field is reduced below
the release point, BRP , the device output goes high (turns off).
The output of the A1125 devices switches high (turns off) when
a magnetic field perpendicular to the Hall element exceeds the
operate point threshold, BOP (see panel B of figure 1). When the
magnetic field is reduced below the release point, BRP , the device
output goes low (turns on).
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.
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. Powering-on the device
in the hysteresis range (less than BOP and higher than BRP) will
BRP
B+
• Hall-Effect IC Applications Guide, Application Note 27701
• Guidelines for Designing Subassemblies Using Hall-Effect
Devices, Application Note 27703.1
• Soldering Methods for Allegro’s Products – SMT and ThroughHole, Application Note 26009
All are provided on the Allegro Web site, www.allegromicro.com.
0
Switch to High
VCC
0
BHYS
BHYS
(A)
(B)
RL
A112x
VOUT
VOUT(SAT)
BOP
BOP
0
Extensive applications information for Hall effect devices is
available in:
VCC
VOUT
VOUT
VOUT(SAT)
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 external noise in the
application. As is shown in panel B of figure 1, a 0.1 µF capacitor
is typical.
VS
Switch to Low
0
Switch to Low
Switch to High
VCC
Applications
V+
BRP
V+
give an indeterminate output state. The correct state is attained
after the first excursion beyond BOP or BRP .
CBYP
0.1 µF
Output
GND
B+
(C)
Figure 1. Device switching behavior. In panels A and B, on the horizontal axis, the B+ direction indicates increasing south polarity magnetic
field strength. This behavior can be exhibited when using an electrical circuit such as that shown in panel C.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision 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 element. 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 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 magnetic sourced signal
then can pass through a low-pass filter, while the modulated DC
offset is suppressed. This configuration is illustrated in figure 2.
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 (800 kHz). 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.
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 device 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. Model of chopper stabilization technique
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision 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 website.)
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)
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 1.6 mA, and RθJA = 165°C/W, then:
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.
Example: Reliability for VCC at TA = 150°C, package LH, using a
minimum-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) = 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 ÷ 228 °C/W = 66 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 66 mW ÷ 4 mA = 16.5 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.
PD = VCC × ICC = 12 V × 1.6 mA = 19 mW
ΔT = PD × RθJA = 19 mW × 165°C/W = 3°C
TJ = TA + ΔT = 25°C + 3°C = 28°C
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
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
8X 10° REF
B
PCB Layout Reference View
C
Standard Branding Reference View
Branded Face
1.00 ±0.13
0.95 BSC
0.40 ±0.10
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
NNT
+0.10
0.05 –0.05
1
N = Last two digits of device part number
T = Temperature code (letter)
NNN
1
N = Last three digits of device part number
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
15
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
Package UA, 3-Pin SIP, Matrix Style
+0.08
4.09 –0.05
45°
B
D Standard Branding Reference View
E
C
2.04
1.52 ±0.05
+0.08
3.02 –0.05
1.44
E
Mold Ejector
Pin Indent
E
Branded
Face
A
1.02
MAX
NNN
10°
1
= Supplier emblem
N = Last three digits of device part number
45°
0.79 REF
NNT
1
2
1
3
= Supplier emblem
N = Last two digits of device part number
T = Temperature code
+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
16
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
Package UA, 3-Pin SIP, Chopper Style
+0.08
4.09 –0.05
45°
B
C
E
2.04
1.52 ±0.05
1.44 E
Mold Ejector
Pin Indent
+0.08
3.02 –0.05
E
Branded
Face
45°
1
2.16
MAX
D Standard Branding Reference View
0.79 REF
0.51
REF
NNT
NOT FOR
NEW DESIGN
A
1
2
3
+0.03
0.41 –0.06
15.75 ±0.51
= Supplier emblem
N = Last two digits of device part number
T = Temperature code
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
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
17
A1120, A1121, A1122,
A1123, and A1125
Chopper-Stabilized Precision Hall-Effect Switches
Revision History
Number
Date
Description
15
September 3, 2013
Update product offerings;
Update UA package drawing
16
September 16, 2015
Added AEC-Q100 qualification under Features and Benefits
17
November 4, 2016
Chopper-style UA package designated as not for new design
Copyright ©2016, 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
18
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