A3240
Chopper-Stabilized, Precision Hall-Effect Switch
Not for New Design
These parts are in production but have been determined to be
NOT FOR NEW DESIGN. This classification indicates that sale of
this device is currently restricted to existing customer applications.
The device should not be purchased for new design applications
because obsolescence in the near future is probable. Samples are no
longer available.
Date of status change: May 4, 2009
Recommended Substitutions:
The replacement part is the
A1120
next-generation chopper-stabilized
switch.
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.
A3240
Chopper-Stabilized, Precision
Hall-Effect Switch
Features and Benefits
▪
Resistant to Physical Stress
▪
Superior Temperature Stability
▪
Output Short-Circuit Protection
▪
Operation From Unregulated Supply
▪
Reverse Battery Protection
▪
Solid-State Reliability
▪
Small Size
Description
The A3240 Hall-effect switch is an extremely tempera-
ture-stable and stress-resistant sensor especially suited for
operation over extended temperature ranges to +150°C.
Superior high-temperature performance is made possible
through dynamic offset cancellation, which reduces the
residual offset voltage normally caused by device overmolding,
temperature dependencies, and thermal stress.
The 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-collector output to sink up to 25 mA. A south pole of
sufficient strength will turn the output on. An on-board regulator
permits operation with supply voltages of 4.2 to 24 volts.
Three package styles provide a magnetically optimized package
for most applications. Package type LH is a modified SOT23W
surface-mount package, LT is a miniature SOT89/TO-243AA
transistor package for surface-mount applications; while UA is
a three-lead ultra-mini-SIP for through-hole mounting. The LH
and UA packages are also available in a lead (Pb) free version
(suffix,
–T)
, with a 100% matte tin plated leadframe.
Packages:
3-pin SOT89
(LT package)
3-pin SOT23W
(LH package)
3-pin SIP
(UA package)
Not to scale
Functional Block Diagram
SUPPLY
REG.
TO ALL
SUBCIRCUITS
DYNAMIC
OFFSET CANCELLATION
OUTPUT
LOW-PASS
FILTER
SAMPLE
& HOLD
X
CONTROL
CURRENT
LIMIT
<1
GROUND
Dwg. FH-020-1
27621.20h
A3240
Chopper-Stabilized, Precision Hall-Effect Switch
Selection Guide
Part Number
A3240ELHLT-T
A3240ELTTR-T
A3240EUA-T
A3240LLHLT-T
A3240LLTTR-T
A3240LUA-T
*
Contact
Packing
*
Mounting
Ambient, T
A
(ºC)
–40 to 85
B
RP(MIN)
(G)
B
OP(MAX)
(G)
7-in. reel, 3000 pieces/reel Surface Mount
7-in. reel, 1000 pieces/reel Surface Mount
Bulk, 500 pieces/bag
SIP through hole
–40 to 150
7-in. reel, 3000 pieces/reel Surface Mount
7-in. reel, 1000 pieces/reel Surface Mount
Bulk, 500 pieces/bag
SIP through hole
5.0
50
Allegro for additional packing options.
Absolute Maximum Ratings
Characteristic
Supply Voltage
Reverse Battery Voltage
Output Off Voltage
Continuous Output Current
Reverse Output Current
Package Power Dissipation
Magnetic Flux Density
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
V
CC
V
RCC
V
OUT
I
OUT
I
ROUT
P
D
B
T
A
T
J
(max)
T
stg
1 G = 0.1 mT (millitesla)
Range E
Range L
Internal current limiting is intended to protect the
device from output short circuits.
Notes
Rating
26.5
–30
26
25
–50
See graph
Unlimited
–40 to 85
–40 to 150
165
–65 to 170
Unit
V
V
V
mA
mA
W
G
ºC
ºC
ºC
ºC
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A3240
Chopper-Stabilized, Precision Hall-Effect Switch
Suffix ‘–LT’ & ‘–UA’ Pinning
(SOT89/TO-243AA & ultra-min SIP)
Suffix ‘–LH’ Pinning
(SOT23W)
3
X
PTCT
PTCT
V
CC
V
CC
1
1
2
3
2
GROUND
SUPPLY
OUTPUT
Dwg. PH-003-4
Dwg. PH-003-2
Pinning is shown viewed from branded side.
Package Power Dissipation
800
700
Suffix "–UA"
R
θJA
= 165°C/W
600
500
Suffix "–LH"
R
θJA
= 228°C/W
Suffix "–LT"
R
θJA
= 180°C/W
400
300
200
Suffix "E–"
100
Suffix "L–"
0
20
40
60
80
120
100
AMBIENT TEMPERATURE in °C
140
160
180
Dwg. GH-046-2D
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
Copyright © 2000, 2003 Allegro MicroSystems, Inc.
A3240
Chopper-Stabilized, Precision Hall-Effect Switch
ELECTRICAL CHARACTERISTICS over operating temperature range.
Limits
Characteristic
Supply Voltage Range
Output Leakage Current
Output Saturation Voltage
Output Current Limit
Power-On Time
Chopping Frequency
Output Rise Time
Output Fall Time
Supply Current
Symbol
V
CC
I
OFF
V
OUT(SAT)
I
OM
t
po
f
C
t
r
t
f
I
CC
R
L
= 820
,
C
L
= 20 pF
R
L
= 820
,
C
L
= 20 pF
B < B
RP
, V
CC
= 12 V
B > B
OP
, V
CC
= 12 V
Reverse Battery Current
Zener Voltage
Zener Impedance
I
CC
V
Z
+ V
D
z
z
+ z
D
V
RCC
= -30 V
I
CC
= 15 mA, T
A
= 25°C
I
CC
= 15 mA, T
A
= 25°C
Test Conditions
Operating, T
J
< 170°C
1
V
OUT
= 24 V, B < B
RP
I
OUT
= 20 mA, B > B
OP
B > B
OP
V
CC
> 4.2 V
Min.
4.2
–
–
30
–
–
–
–
–
–
–
28
–
Typ.
–
–
185
–
–
340
0.2
0.1
3.0
4.0
–
32
50
Max.
24
10
500
60
50
–
2.0
2.0
6.0
6.0
-5.0
37
–
Units
V
μA
mV
mA
μs
kHz
μs
μs
mA
mA
mA
V
NOTES: 1. Maximum voltage must be adjusted for power dissipation and junction temperature.
2. B
OP
= operate point (output turns on); B
RP
= release point (output turns off).
3. Typical Data is at T
A
= +25°C and V
CC
= 12 V and is for design information only.
MAGNETIC CHARACTERISTICS over operating supply voltage and temperature ranges.
Characteristic
Operate Point
Release Point
Hysteresis
Symbol
B
OP
B
RP
B
hys
B
OP
- B
RP
Test Conditions
Min.
–
5.0
–
Limits
Typ.
Max.
35
25
10
50
–
–
Units
G
G
G
NOTES: 1. Typical Data is at T
A
= +25°C and V
CC
= 12 V and is for design information only.
2. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
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