A3211 and A3212
Micropower, Ultrasensitive
Hall-Effect Switches
Features and Benefits
▪
▪
▪
▪
Micropower operation
Operation with north or south pole
2.5 to 3.5 V battery operation
Chopper stabilized
▫
Superior temperature stability
▫
Extremely low switchpoint drift
▫
Insensitive to physical stress
High ESD protection
Solid-state reliability
Small size
Easily manufacturable with magnet pole independence
Description
The A 3211 and A3212 integrated circuits are ultrasensitive,
pole independent Hall-effect switches with latched digital
output. These devices are especially suited for operation
in battery-operated, hand-held equipment such as cellular
and cordless telephones, pagers, and palmtop computers.
A 2.5 to 3.5 V operation and a unique clocking scheme reduce
the average operating power requirements to less than 15
W
with a 2.75 V supply.
Unlike other Hall-effect switches, either a north or south pole
of sufficient strength will turn the output on in the A3212,
and in the absence of a magnetic field, the output is off. The
A3211 provides an inverted output. The polarity independence
and minimal power requirements allow these devices to easily
replace reed switches for superior reliability and ease of
manufacturing, while eliminating the requirement for signal
conditioning.
Improved stability is made possible through chopper
stabilization (dynamic offset cancellation), which reduces the
residual offset voltage normally caused by device overmolding,
temperature dependencies, and thermal stress.
▪
▪
▪
▪
Packages:
DFN (EH)
DFN (EL)
SOT23W (LH)
Not to scale
SIP (UA)
Continued on the next page…
Functional Block Diagram
SUPPLY
SWITCH
TIMING
LOGIC
DYNAMIC
OFFSET CANCELLATION
OUTPUT
SAMPLE
& HOLD
LATCH
X
GROUND
Dwg. FH-020-5
3211-DS, Rev. 18
A3211
and
A3212
Micropower, Ultrasensitive
Hall-Effect Switches
Description (continued)
This device includes on a single silicon chip a Hall-voltage gen-
erator, small-signal amplifier, chopper stabilization, a latch, and
a MOSFET output. Advanced CMOS processing is used to take
advantage of low-voltage and low-power requirements, compo-
nent matching, very low input-offset errors, and small component
geometries.
Four package styles provide magnetically optimized solutions for
most applications. Miniature low-profile surface-mount package
types
EH
and
EL
(0.75 and 0.50 mm nominal height) are leadless,
LH
is a 3-pin low-profile SMD, and
UA
is a three-pin SIP for
through-hole mounting. Packages are lead (Pb) free (suffix,
–T)
with 100% matte tin plated leadframes.
Selection Guide
Part Number
A3211EEHLT–T
2
A3211EELLT–T
2
A3211ELHLT–T
A3212EEHLT–T
2,3
A3212EELLT–T
2
A3212ELHLT–T
A3212EUA–T
A3212LLHLT–T
A3212LUA–T
1
Contact Allegro
2
Allegro
Packing
1
3000 pieces per reel
3000 pieces per reel
3000 pieces per reel
3000 pieces per reel
3000 pieces per reel
3000 pieces per reel
500 pieces per bulk bag
3000 pieces per reel
500 pieces per bulk bag
Package
2 mm x 3 mm, 0.75 mm nominal height DFN
2 mm x 2 mm, 0.50 mm nominal height DFN
3-pin surface mount SOT23W
2 mm x 3 mm, 0.75 mm nominal height DFN
2 mm x 2 mm, 0.50 mm nominal height DFN
3-pin surface mount SOT23W
SIP-3 through hole
3-pin surface mount SOT23W
SIP-3 through hole
Ambient Temperature
T
A
(°C)
–40 to 85
State in
Magnetic Field
Off
–40 to 85
On
–40 to 150
for additional packaging and handling options.
products sold in DFN package types are not intended for automotive applications.
3
Variant is in production but has been determined to be NOT FOR NEW DESIGN. This classification indicates that sale of the variant is cur-
rently restricted to existing customer applications. The variant should not be purchased for new design applications because obsolescence in
the near future is probable. Samples are no longer available. Status change: December 3, 2013. Recommended substitute: A3212EELLT-T.
Absolute Maximum Ratings
Characteristic
Supply Voltage
Magnetic Flux Density
Output Off Voltage
Output Current
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
V
DD
B
V
OUT
I
OUT
T
A
T
J
(max)
T
stg
Range E
Range L
Notes
Rating
5
Unlimited
5
1
–40 to 85
–40 to 150
165
–65 to 170
Units
V
G
V
mA
ºC
ºC
ºC
ºC
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A3211
and
A3212
Micropower, Ultrasensitive
Hall-Effect Switches
Package Suffix ‘EL’ Pinning
(Leadless Chip Carrier)
Package Suffix ‘EH’ Pinning
(Leadless Chip Carrier)
NO
CONNECTION
Dwg. PH-016-2
GROUND
SUPPLY
6
V
DD
5
4
3
X
V
1
OUTPUT
DD
2
NO
CONNECTION
3
GROUND
1
2
GROUND
Dwg. PH-016-1
Package Suffix ‘LH’ Pinning
(SOT23W)
Package Suffix ‘UA’ Pinning
(SIP)
3
X
V
DD
V
DD
1
2
1
2
3
GROUND
OUTPUT
SUPPLY
GROUND
Dwg. PH-016-1
Dwg. PH-016
Pinning is shown viewed from branded side.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
OUTPUT
SUPPLY
OUTPUT
SUPPLY
3
A3211
and
A3212
Micropower, Ultrasensitive
Hall-Effect Switches
ELECTRICAL CHARACTERISTICS
over operating voltage and temperature range (unless otherwise specified).
Characteristic
Supply Voltage Range
Output Leakage Current
Output On Voltage
Awake Time
Period
Duty Cycle
Chopping Frequency
Symbol
V
DD
I
OFF
V
OUT
t
awake
t
period
d.c.
f
C
I
DD(EN)
Supply Current
I
DD(DIS)
I
DD(AVG)
Chip awake (enabled)
Chip asleep (disabled)
V
DD
= 2.75 V
Test Conditions
Operating
V
OUT
= 3.5 V, Output off
I
OUT
= 1 mA, V
DD
= 2.75 V
Limits
Min.
2.5
–
–
–
–
–
–
–
–
–
–
Typ.*
2.75
<1.0
100
45
45
0.1
340
–
–
5.1
6.7
Max.
3.5
1.0
300
90
90
–
–
2.0
8.0
10
10
Units
V
μA
mV
μs
ms
%
kHz
mA
μA
μA
μA
V
DD
= 3.5 V
* Typical data is at T
A
= 25°C and V
DD
= 2.75 V, and is for design information only.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A3211
and
A3212
Micropower, Ultrasensitive
Hall-Effect Switches
A3211 MAGNETIC CHARACTERISTICS
over operating voltage range (unless otherwise specified)
Characteristic
Symbol
Test Conditions
Limits
Min.
–
–55
10
–
–
Typ.
37
–40
31
–34
5.9
Max.
55
–
–
–10
–
Units
G
G
G
G
G
Over Temperature Range E: T
A
= –40°C to 85°C
Operate Points
Release Points
Hysteresis
B
OPS
B
OPN
B
RPS
B
RPN
B
HYS
South pole to branded side; B > B
OP
, V
OUT
= High (Output Off)
North pole to branded side; B > B
OP
, V
OUT
= High (Output Off)
South pole to branded side; B < B
RP
, V
OUT
= Low (Output On)
North pole to branded side; B < B
RP
, V
OUT
= Low (Output On)
|B
OPx
- B
RPx
|
NOTES: 1. Negative flux densities are defined as less than zero (algebraic convention), i.e., -50 G is less than +10 G.
2. B
OPx
= operate point (output turns off); B
RPx
= release point (output turns on).
3. Typical Data is at T
A
= +25°C and V
DD
= 2.75 V and is for design information only.
4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
A3212 MAGNETIC CHARACTERISTICS
over operating voltage range (unless otherwise specified)
Characteristic
Symbol
Test Conditions
Limits
Min.
–
–55
10
–
–
–
–65
10
–
–
Typ.
37
–40
31
–34
5.9
37
–40
31
–34
5.9
Max.
55
–
–
–10
–
65
–
–
–10
–
Units
G
G
G
G
G
G
G
G
G
G
Over Temperature Range E: T
A
= –40°C to 85°C
Operate Points
Release Points
Hysteresis
B
OPS
B
OPN
B
RPS
B
RPN
B
HYS
B
OPS
B
OPN
B
RPS
B
RPN
B
HYS
South pole to branded side; B > B
OP
, V
OUT
= Low (Output On)
North pole to branded side; B > B
OP
, V
OUT
= Low (Output On)
South pole to branded side; B < B
RP
, V
OUT
= High (Output Off)
North pole to branded side; B < B
RP
, V
OUT
= High (Output Off)
|B
OPx
- B
RPx
|
South pole to branded side; B > B
OP
, V
OUT
= Low (Output On)
North pole to branded side; B > B
OP
, V
OUT
= Low (Output On)
South pole to branded side; B < B
RP
, V
OUT
= High (Output Off)
North pole to branded side; B < B
RP
, V
OUT
= High (Output Off)
|B
OPx
- B
RPx
|
Over Temperature Range L: T
A
= –40°C to 150°C
Operate Points
Release Points
Hysteresis
NOTES: 1. Negative flux densities are defined as less than zero (algebraic convention), i.e., -50 G is less than +10 G.
2. B
OPx
= operate point (output turns on); B
RPx
= release point (output turns off).
3. Typical Data is at T
A
= +25°C and V
DD
= 2.75 V and is for design information only.
4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
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