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2 x 2 mm MLPD
EL Package
A321 1 and A3212
MICROPOWER, ULTRA-SENSITIVE
HALL-EF FECT SWITCHES
The A 3211 and A3212 integrated circuits are ultra-sensitive, pole in de pen dent
Hall-effect switches with latched digital output. These sensors are es pe cial ly
suited for operation in battery-operated, hand-held equip ment such as cellular
and cordless tele phones, pagers, and palmtop com put ers. A 2.5 volt to 3.5 volt
operation and a unique clocking scheme reduce the average op er at ing power
requirements to less than 15 μW with a 2.75 volt supply.
Unlike other Hall-effect switches, either a north or south pole of suf fi cient
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.
Approximate actual size
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
Magnetic Flux Density, B .......... Unlimited
Output Off Voltage, V
Output Current, I
Junction Temperature, T
Operating Temperature, TA
Range 'E-' .................... -40°C to +85°C
Range 'L-' .................. -40°C to +150°C
Storage Temperature Range,
T
.............................. -65°C to +170°C
S
.............................. 5 V
DD
...................... 5 V
OUT
........................... 1 mA
OUT
................ +170°C
J
Improved stability is made possible through chopper stabilization (dynamic offset cancellation), which reduces the residual offset voltage normally caused by
device overmolding, temperature de pen den cies, and thermal stress.
This device includes on a single silicon chip a Hall-voltage generator, small-signal amplifier, chopper sta bi li za tion, a latch, and a MOSFET output. Ad vanced
BiCMOS processing is used to take advantage of low-voltage and low-power
requirements, component matching, very low input-offset errors, and small component geometries.
Four package styles provide magnetically op ti mized solutions for most ap pli -
ca tions. Miniature low-profile surface-mount package types EH and EL
(0.75 and 0.50 mm nominal height) are leadless, LH is a leaded low-profile
SMD, and UA is a three-lead SIP for through-hole mount ing. Packages are available in lead (Pb) free versions (suffix, –T) with 100% matte tin plated leadframe.
EL package for limited release, engineering samples available.
FEATURES
■ Micropower Operation
■ Operation with North or
■ 2.5 V to 3.5 V Battery Operation
■ Chopper Stabilized
Superior Temperature Stability
Extremely Low Switch-Point Drift
Insensitive to Physical Stress
■ High ESD Protection
■ Sol id-State Reliability
■ Small Size
■ Easily Manufacturable with Magnet Pole Independence
South Pole
A3211-DS, Rev. 2
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
Use complete part numbers when ordering
Product Selection Guide
Part Number Pb-free
A3211EEHLT–T Yes Tape and Reel (3000)
A3211ELHLT–T Yes Tape and Reel (3000) 3-Pin Surface Mount
A3212EEHLT – Tape and Reel (3000)
A3212EEHLT–T Yes Tape and Reel (3000)
A3212EELLT–T Yes Tape and Reel (3000)
A3212ELHLT – Tape and Reel (3000)
A3212ELHLT–T Yes Tape and Reel (3000)
A3212EUA – Bulk Pack (500)
A3212EUA–T Yes Bulk Pack (500)
A3212LLHLT
A3212LLHLT–T Yes Tape and Reel (3000)
A3212LUA
A3212LUA–T Yes Bulk Pack (500)
1
Contact Allegro for additional packaging and handling options.
2
These variants are in production but have been determined to be NOT FOR NEW DESIGN. This classification indicates that sale of this device is cur-
rently 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. Status date change October 31, 2005.
2
2
– Tape and Reel (3000)
– Bulk Pack (500)
Packing
(Units/Pack)
1
Package
Leadless Surface Mount
Leadless Surface Mount
3-Pin Surface Mount
SIP-3 Through Hole, Straight Lead
3-Pin Surface Mount
SIP-3 Through Hole, Straight Lead
Ambient
Temperature
(°C)
T
A
–40 to 85A3211EELLT–T Yes Tape and Reel (3000)
–40 to 85
–40 to 150
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
SUPPLY
SWITCH
FUNCTIONAL BLOCK DIAGRAM
TIMING
LOGIC
OUTPUT
X
DYNAMIC
OFFSET CANCELLATION
& HOLD
SAMPLE
LATCH
GROUND
Dwg. FH-020-5
3
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
A321 1 and A3212
X
Dwg. PH-016-2
SUPPLY
GROUND
OUTPUT
V
DD
GROUND
NO
CONNECTION
NO
CONNECTION
5
4
6
1
3
2
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
Package Suffix ‘EH’ Pinning
(Leadless Chip Carrier)
Package Suffix ‘EL’ Pinning
(Leadless Chip Carrier)
3
V
DD
12
SUPPLY
GROUND
OUTPUT
Dwg. PH-016-1
Package Suffix ‘LH’ Pinning
(SOT23W)
Package Suffix ‘UA’ Pinning
(SIP)
3
X
V
DD
V
DD
12
SUPPLY
GROUND
Dwg. PH-016-1
OUTPUT
Pinning is shown viewed from branded side.
1
SUPPLY
32
GROUND
Dwg. PH-016
OUTPUT
www.allegromicro.com
4
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless otherwise specified).
Characteristic Symbol Test Conditions
Supply Voltage Range V
Output Leakage Current I
Output On Voltage V
Awake Time t
Period t
Duty Cycle d.c. – 0.1 – %
Chopping Frequency f
Supply Current
* Typical data is at T
= 25°C and VDD = 2.75 V, and is for design information only.
A
DD
OFF
OUT
awake
period
C
I
DD(EN)
I
DD(DIS)
I
DD(AVG)
Operating 2.5 2.75 3.5 V
V
= 3.5 V, Output off – <1.0 1.0 μA
OUT
I
= 1 mA, VDD = 2.75 V – 100 300 mV
OUT
Chip awake (enabled) – – 2.0 mA
Chip asleep (disabled) – – 8.0 μA
VDD = 2.75 V – 5.1 10 μA
= 3.5 V – 6.7 10 μA
V
DD
Min. Typ.* Max. Units
–4590μs
–4590ms
– 340 – kHz
Limits
5
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
3211 MAGNETIC CHARACTERISTICS over operating voltage and temperature range (unless otherwise specified)
Characteristic Symbol Test Conditions
Operate Points
Release Points
Hysteresis B
B
B
B
B
South pole to branded side; B > BOP, V
OPS
North pole to branded side; B > BOP, V
OPN
South pole to branded side; B < BRP, V
RPS
North pole to branded side; B < BRP, V
RPN
|B
- B
HYS
OPx
| – 5.9 – G
RPx
Min. Typ. Max. Units
= High (Output Off) – 37 55 G
OUT
= High (Output Off) –55 –40 – G
OUT
= Low (Output On) 10 31 – G
OUT
= Low (Output On) – –34 –10 G
OUT
Limits
NOTES: 1. Negative flux densities are defined as less than zero (algebraic convention), i.e., -50 G is less than +10 G.
2. B
= operate point (output turns off); B
OPx
= release point (output turns on).
RPx
3. Typical Data is at TA = +25°C and VDD = 2.75 V and is for design information only.
4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
3212 MAGNETIC CHARACTERISTICS over operating voltage and temperature range (unless otherwise specified)
Characteristic Symbol Test Conditions
Operate Points
Release Points
Hysteresis B
B
B
B
B
South pole to branded side; B > BOP, V
OPS
North pole to branded side; B > BOP, V
OPN
South pole to branded side; B < BRP, V
RPS
North pole to branded side; B < BRP, V
RPN
|B
- B
HYS
OPx
| – 5.9 – G
RPx
= Low (Output On) – 37 55 G
OUT
= Low (Output On) –55 –40 – G
OUT
= High (Output Off) 10 31 – G
OUT
= High (Output Off) – –34 –10 G
OUT
Min. Typ. Max. Units
NOTES: 1. Negative flux densities are defined as less than zero (algebraic convention), i.e., -50 G is less than +10 G.
2. B
= operate point (output turns on); B
OPx
= release point (output turns off).
RPx
3. Typical Data is at TA = +25°C and VDD = 2.75 V and is for design information only.
4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
6
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Limits
A321 1 and A3212
60
SWITCH POINTS IN GAUSS
20
0
-20
-40
2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE IN VOLTS
2.4
Dwg. GH-057-2
2.6
B
OPS
-60
40
B
RPS
B
RPN
B
OPN
TA = 25°C
1
0
7.0
AVERAGE SUPPLY CURRENT IN μμ
μμ
A
6.0
5.0
4.0
3.0
2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE IN VOLTS
2.4
Dwg. GH-058-7
2.6
TA = 25°C
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
TYPICAL OPERATING CHARACTERISTICS
SWITCH POINTS
60
B
40
20
OPS
B
RPS
0
-20
SWITCH POINTS IN GAUSS
-40
-60
-50
7.0
A
μμ
6.0
VDD = 2.75 V
B
RPN
B
OPN
-25 25 75 125
0 50 100
AMBIENT TEMPERATURE IN °°°°C
SUPPLY CURRENT
VDD =3.5 V
150
Dwg. GH-027-3
5.0
4.0
AVERAGE SUPPLY CURRENT IN μμ
3.0
-50
-25
www.allegromicro.com
VDD =2.75 V
VDD =2.5 V
100
0255075
AMBIENT TEMPERATURE IN °°°°C
125
Dwg. GH-028-1
15
7
A321 1 and A3212
+V
HALL
VOLTAGE
B
+
—
Dwg. AH-011-2
Dwg. EH-012-1
SAMPLE
& HOLD
X
+V
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
FUNCTIONAL DESCRIPTION
Low Average Power. Internal timing circuitry activates the
sensor for 45 μs and deactivates it for the remainder of the period (45 ms). A short "awake" time allows for stabilization prior
to the sensor sam pling and data latching on the falling edge of
the timing pulse. The output during the "sleep" time is latched in
the last sampled state. The supply current is not affected by the
output state.
PERIOD
IDD(EN)
"AWAKE"
"SLEEP"
SAMPLE &
OUTPUT LATCHED
IDD(DIS)
0
Dwg. WH-017-2
Chopper-Stabilized Technique. The Hall element can be
considered as a resistor array similar to a Wheatstone bridge. A
large portion of the offset is a result of the mismatching of these
resistors. These devices use a proprietary dynamic offset cancellation technique, with an internal high-frequency clock to reduce
the residual offset voltage of the Hall element that is normally
caused by device overmolding, temperature de pen den cies, and
thermal stress. The chopper-stabilizing technique cancels the
mismatching of the resistor circuit by changing the direction of
the current flowing through the Hall plate using CMOS switches
and Hall voltage measurement taps, while maintaing the Hallvoltage signal that is induced by the external magnetic flux. The
signal is then captured by a sample-and-hold circuit and further
processed using low-offset bipolar circuitry. This technique
produces devices that have an extremely stable quiescent Hall
output voltage, are immune to thermal stress, and have precise
recoverability after temperature cycling. A relatively high sampling frequency is used for faster signal processing capability
can be processed.
More detailed descriptions of the circuit operation can be found
in: Technical Paper STP 97-10, Monolithic Magnetic Hall Sensor
Using Dynamic Quadrature Offset Cancellation and Technical
Paper STP 99-1, Chopper-Stabilized Amplifiers With A Track-
and-Hold Signal Demodulator.
8
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
FUNCTIONAL DESCRIPTION (cont'd)
0
+B
0
-B
OUTPUT ON
OUTPUT ON
5V
MAX
B
OPS
B
RPS
B
OPN
B
RPN
OUTPUT VOLTAGE
MAGNETIC FLUX
A3212
OUTPUT OFF
0
+B
0
-B
5V
MAX
OUTPUT VOLTAGE
MAGNETIC FLUX
OUTPUT OFF
OUTPUT OFF
B
RPS
OPS
B
OPN
RPN
OUTPUT ON
B
A3211
B
Operation. The output of the A3212 switches low (turns on)
when a magnetic field perpendicular to the Hall sensor exceeds
the operate point B
output is capable of sinking up to 1 mA and the output voltage
is V
OUT(ON)
release point B
. When the magnetic field is reduced below the
RPS
switches high (turns off). The dif fer ence in the magnetic operate
and release points is the hysteresis (B
built-in hysteresis allows clean switching of the output even
in the presence of external mechanical vibration and electrical
noise. The A3211 functions in the same manner, except the output voltage is reversed from the A3212, as shown in the figures
to the right.
(or is less than B
OPS
(or increased above B
hys
). After turn-on, the
OPN
), the device output
RPN
) of the device. This
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
As used here, negative flux densities are defined as less than
zero (algebraic convention), i.e., -50 G is less than +10 G.
Applications. Allegro's pole-independent sensing technique
allows for operation with either a north pole or south pole magnet orientation, enhancing the manufacturability of the device.
The state-of-the-art technology provides the same output polarity
for either pole face.
It is strongly recommended that an external bypass ca pac i tor
be con nect ed (in close proximity to the Hall sensor) between the
supply and ground of the device to reduce both external noise
and noise generated by the chopper-sta bi li za tion tech nique. This
is especially true due to the relatively high im ped ance of battery
supplies.
The sim plest form of magnet that will op er ate these devices
is a bar magnet with either pole near the branded surface of the
device. Many oth er meth ods of operation are possible. Ex ten sive applications information for Hall-effect sensors is available
in:
• Hall-Effect IC Applications Guide, Application Note 27701;
• Hall-Effect Devices: Soldering, Gluing, Potting, En cap su -
lat ing, and Lead Forming, Application Note 27703.1;
• Soldering of Through-Hole Hall-Sensor Dervices, Application
Note 27703; and
• Soldering of Surface-Mount Hall-Sensor Devices, Application
Note 27703.2.
All are provided at
www.allegromicro.com
2
3
X
1
DD
V
0.1 ∝F
OUTPUT
50 k
SUPPLY
(3 V B ATTE R Y)
Dwg. EH-013-2
www.allegromicro.com
9
A321 1 and A3212
Package Designator 'UA'
1 32
Dwg. MH-011-13
0.0195"
0.50 mm
NOM
BRANDED
SURFACE
ACTIVE AREA DEPTH
0.078"
1.98 mm
0.052"
1.32 mm
A
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
SENSOR LOCATIONS
Package Designator 'EH'
ACTIVE AREA DEPTH
0.013"
0.34 mm
NOM
BRANDED
SURFACE
Package Designator 'LH'
0.035"
0.88 mm
654
1.56 mm
A
12
3
Dwg. MH-030
0.062"
Package Designator 'EL'
ACTIVE AREA DEPTH
0.006"
0.16 mm
NOM
BRANDED
SURFACE
A
.0406
1.03 mm
3
1
2
.0291
0.74 mm
ACTIVE AREA DEPTH
10
0.011"
0.28 mm
NOM
A
1
0.056"
1.42 mm
3
0.033"
0.84 mm
2
Dwg. MH-025-2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
PACKAGE DESIGNATOR ‘EH'
(Reference MO-229C WCED-1)
2.15
.085
1.85
.073
6
3.15
.124
2.85
.112
A
1
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
3.70
BSC
.146
1.25
BSC
1.00
BSC
0.25
BSC
0.30
BSC
.049
0.25
BSC
0.50
BSC
.039
.010
.012
.010
.020
0.30
.012
0.20
.008
0.50
.020
BSC
6
1.142
0.892
1
B
6
.045
.035
0.65
.026
0.45
1.324
1.074
.018
.052
.042
C
1
0.40
BSC
0.95
BSC
.016
.037
0.05
0.00
Dimensions in millimeters
U.S. Customary dimensions (in.) in brackets, for reference only
A
Pin index area
B
Exposed thermal pad
C
ø0.3 Thermal via (optional)
.002
.000
0.20
REF
0.80
0.70
.008
.031
.028
www.allegromicro.com
11
PACKAGE DESIGNATOR ‘EL'
MLPD 3 Contact
2.00
.079
BSC
3
2.00
.079
BSC
A
21
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
1.025
MAX
0.20
REF
0.15
MIN
0.40
NOM
0.32
MIN
.040
.006
.008
.016
.013
1.350
BSC
.053
0.32
.013
0.20
.008
0.50
.053
.043
BSC
.020
0.05
0.80
0.00
0.325
REF
0.70
.013
1
2
B
3
0.325
.013
REF
0.50
3
D
0.138
.005
0.50
BSC
REF
.020
2.40
REF
.094
C
1
0.30
R0.200
REF
.020
.012
.008
1.350
1.100
.002
.031
.000
.028
0.138
REF
0.15
REF
1.025
0.775
.005
0.55
0.45
.006
.040
.031
.022
.018
Dimensions in millimeters
U.S. Customary dimensions (in.)
in brackets, for reference only
A
Pin index area
B
Exposed thermal pad
C
Optional thermal vias, ∅0.30 [.012], pitch 1.2 [.047]
D
Typical pad layout; adjust as necessary to
meet application process requirements
www.allegromicro.com
12
7
0.020
0.012
0.122
0.114
Dimensions in Inches
(for reference only)
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
PACKAGE DESIGNATOR ‘LH’
(SOT23W, fits SC-59A solder-pad layout)
Dimensions in Millimeters
(controlling dimensions)
3.10
2.90
0.50
0.30
0.083
0.073
0.022
REF
0.006
0.000
3
12
0.118
0.106
0.037
BSC
0.039
GAUGE PLANE
SEATING PLANE
0°TO8°
0.0079
0.0050
0.045
0.032
0.028
3
0.094
12
0.010
BSC
Dwg. MA-010-3D in
0.010
MIN
0.55
REF
0.15
0.00
2.10
1.85
3
12
3.00
2.70
0.95
BSC
1.00
12
GAUGE PLANE
SEATING PLANE
0.20
0.127
1.13
0.87
0.70
3
2.40
0°TO8°
0.25
BSC
0.25
MIN
Dwg. MA-010-3D mm
0.03
Dwg. MA-011-3 in
0.95
Dwg. MA-011-3 mm
NOTES: 1. Tolerances on package height and width represent allowable mold offsets. Dimensions given are
measured at the widest point (parting line).
2. Exact body and lead configuration at vendor’s option within limits shown.
3. Height does not include mold gate flash.
4. Where no tolerance is specified, dimension is nominal.
www.allegromicro.com
13
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
PACKAGE DESIGNATOR ‘UA’
SEE NOTE
45°
0.122
0.117
0.640
0.600
Dimensions in Inches
(controlling dimensions)
0.164
0.159
0.085
123
MAX
0.050
BSC
0.062
0.058
0.031
0.0189
0.0142
0.0173
0.0138
Dwg. MH-014E in
45°
SEE NOTE
Dimensions in Millimeters
(for reference only)
4.17
4.04
45°
3.10
2.97
2.16
123
MAX
16.26
15.24
1.27
BSC
1.57
1.47
45°
0.79
0.44
0.35
0.48
0.36
Dwg. MH-014E mm
NOTES: 1. Tolerances on package height and width represent
allowable mold offsets. Dimensions given are measured
at the widest point (parting line).
2. Exact body and lead configuration at vendor’s option
within limits shown.
3. Height does not include mold gate flash.
4. Recommended minimum PWB hole diameter to clear
transition area is 0.035" (0.89 mm).
5. Where no tolerance is specified, dimension is nominal.
14
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
A321 1 and A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
www.allegromicro.com
The products described herein are man u fac tured under one or
more of the following U.S. pat ents: 5,045,920; 5,264,783; 5,442,283;
5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719;
5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to
time, such de par tures from the detail spec i fi ca tions as may be required
to permit improvements in the per for mance, 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 products are not authorized for use as critical components
in life-support ap pli anc es, devices, or systems without express written
approval.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no re spon si bil i ty
for its use; nor for any infringements of pat ents or other rights of third
parties that may result from its use.
Copyright © 2002, 2003, 2004, 2005 Allegro MicroSystems, Inc.
15
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