A3241 and A3242
Chopper-Stabilized Unipolar Hall-Effect Switches
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: August 1, 2011
Recommended Substitutions:
For existing customer transition, and for new customers or new appli-
cations, refer to the
A1122.
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 respon-
sibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.
A3241 and A3242
Chopper-Stabilized Unipolar Hall-Effect Switches
Features and Benefits
▪
Chopper stabilization
▫
Superior temperature stability
▫
Extremely low switchpoint drift
▫
Insensitive to physical stress
▪
Reverse battery protection
▪
Output short circuit protection
▪
Solid state reliability
▪
Small size
▪
Robust EMC capability
▪
High ESD ratings (HBM)
Description
The A3241 and A3242 integrated circuits are unipolar Hall-
effect switches with digital outputs. These devices are suited
for operation over extended temperature ranges, up to +150°C.
Superior high-temperature performance is made possible
through an Allegro
®
dynamic offset cancellation, which
reduces the residual offset voltage normally caused by
device overmolding, temperature excursions, and thermal
stress.
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.
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.
Packages: 3 pin SOT23W (suffix LH), and
3 pin SIP (suffix UA)
Continued on the next page…
Not to scale
Functional Block Diagram
VCC
Regulator
To All Subcircuits
Sample and Hold
Dynamic Offset
Cancellation
Low-Pass
Filter
VOUT
Amp
Amp
Control
Current Limit
<1Ω
GND
A3241-DS, Rev. 16
A3241
and
A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Description (continued)
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 temperature range. The small geometries of the
BiCMOS process allow these devices to be provided in ultrasmall
packages. The package styles available provide magnetically
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 lead (Pb) free, with 100% matte tin plated leadframes.
Selection Guide
Part Number
A3242LLHLT-T
2
1
Contact Allegro
2
This
Packing
1
7-in. reel, 3000 pieces/reel
Mounting
3-pin SOT23W surface mount
Ambient, T
A
(°C)
–40 to 150
B
RP(MIN)
(G)
110
B
OP(MAX)
(G)
200
for additional packing options.
device is in production, however, it has been deemed Pre-End of Life. The product is approaching end of life. Within a minimum of
6 months, the device will enter its
fi
nal, Last Time Buy, order phase. Status change: August 16, 2010. Recommended substitution: A1122.
Absolute Maximum Ratings
Characteristic
Supply Voltage
Reverse-Supply Voltage
Reverse-Supply Current
Output Off Voltage
Output Current
Magnetic Flux Density
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
V
CC
V
RCC
I
RCC
V
OUT
I
OUTSINK
B
T
A
T
J
(max)
T
stg
Range E
Range L
Notes
Rating
28
–18
–2
28
Internally Limited
Unlimited
–40 to 85
–40 to 150
165
–65 to 170
Units
V
V
mA
V
–
G
ºC
ºC
ºC
ºC
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
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 Voltage
1
Output Leakage Current
Output On Voltage
Output Current Limit
Power-On Time
Chopping Frequency
Output Rise Time
2
Output Fall Time
2
Supply Current
Reverse Battery Current
Supply Zener Clamp Voltage
Supply Zener Current
3
Magnetic Characteristics
4
Operate Point
Release Point
Hysteresis
1
2
Symbol
V
CC
I
OUTOFF
V
OUT(SAT)
I
OM
t
PO
f
c
t
r
t
f
I
CCON
I
CCOFF
I
RCC
V
ZSupply
I
ZSupply
Test Conditions
Operating, T
J
< 165°C
V
OUT
= 24 V, B < B
RP
I
OUT
= 20 mA, B > B
OP
B > B
OP
V
CC
> V
CC(MIN)
R
LOAD
= 820
Ω,
C
S
= 20 pF
R
LOAD
= 820
Ω,
C
S
= 20 pF
B > B
OP
B < B
RP
V
RCC
= –18 V
I
CC
= 6.5 mA; T
A
= 25°C
V
S
= 28 V
A3241
A3242
A3241
A3242
A3241
A3242
B
OP
– B
RP
Min.
3.6
–
–
30
–
–
–
–
–
–
–
28
–
50
120
40
110
10
10
Typ.
–
–
–
–
–
200
–
–
1.5
1.5
–
–
–
95
150
70
125
25
25
Max.
24
10
500
60
50
–
1
1
3.5
3.5
–2
–
6.5
135
200
110
190
42
40
Units
V
μA
mV
mA
μs
kHz
μs
μs
mA
mA
mA
V
mA
G
G
G
G
G
G
B
OP
B
RP
B
HYS
Maximum voltage must be adjusted for power dissipation and junction temperature, see
Power Derating
section.
C
S
= oscilloscope probe capacitance.
3
Maximum current limit is equal to the maximum I
CC(MAX)
+ 3 mA.
4
Magnetic
fl
ux density, B, is indicated as a negative value for north-polarity magnetic
fi
elds, and as a positive value for south-polarity magnetic
fi
elds.
This so-called algebraic convention supports arithmetic comparison of north and south polarity values, where the relative strength of the
fi
eld is indicated
by the absolute value of B, and the sign indicates the polarity of the
fi
eld (for example, a –100 G
fi
eld and a 100 G
fi
eld have equivalent strength, but
opposite polarity).
DEVICE QUALIFICATION PROGRAM
Contact Allegro for information.
EMC (Electromagnetic Compatibility) REQUIREMENTS
Contact Allegro for information.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A3241
and
A3242
Chopper-Stabilized Unipolar Hall Effect Switches
Characteristic Data
Supply Current (On) versus Ambient Temperature
5.0
4.0
I
CCON
(mA)
Supply Current (On) versus Supply Voltage
5.0
4.0
V
CC
(V)
24
3.6
3.0
2.0
1.0
0
T
A
(°C)
–40
25
150
I
CCON
(mA)
3.0
2.0
1.0
0.0
-50
0
50
T
A
(°C)
100
150
0
5
10
V
CC
(V)
15
20
25
Supply Current (Off) versus Ambient Temperature
5.0
4.0
I
CCOFF
(mA)
I
CCOFF
(mA)
Supply Current (Off) versus Supply Voltage
5.0
4.0
3.0
2.0
1.0
0
T
A
(°C)
-40°C
–40
25°C
25
150°C
150
3.0
2.0
1.0
0.0
-50
0
50
T
A
(°C)
100
150
V
CC
(V)
24
3.6
0
5
10
V
CC
(V)
15
20
25
Output Voltage (On) versus Ambient Temperature
500
450
400
V
OUT(SAT)
(mV)
Output Voltage (On) versus Supply Voltage
500
450
400
V
CC
(V)
24
3.6
V
OUT(SAT)
(mV)
350
300
250
200
150
100
50
0
-50
0
50
T
A
(°C)
100
150
350
300
250
200
150
100
50
0
0
5
10
V
CC
(V)
15
20
25
T
A
(°C)
150°C
–40
25°C
25
-40°C
150
Continued on the next page...
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
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