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A3212
MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
The A3212 integrated circuit is an ultra-sensitive, pole independent Hall-effect switch with a latched digital output. This sensor is especially suited for operation in battery-operated, hand-held equipment such as cellular and cordless telephones, pagers, and palmtop computers. A 2.5 volt to 3.5 volt operation and a unique clocking scheme reduce the average operating power requirements to less than 15 W with a 2.75 volt supply. Unlike other Hall-effect switches, either a north or south pole of sufficient strength will turn the output on; in the absence of a magnetic field, the output is off. The polarity independence and minimal power requirement 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. This device includes on a single silicon chip a Hall-voltage generator, small-signal amplifier, chopper stabilization, a latch, and a MOSFET output. Advanced 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 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 leaded low-profile SMD, and UA is a three-lead SIP for through-hole mounting. Each package is available in a lead (Pb) free version (suffix, -T) with 100% matte tin plated leadframe. EL package for limited release, engineering samples available. FEATURES Micropower Operation Operation with North or South Pole 2.5 V to 3.5 V Battery Operation Chopper Stabilized Superior Temperature Stability Extremely Low Switch-Point Drift Insensitive to Physical Stress ESD Protected to 5 kV Solid-State Reliability Small Size Easily Manufacturable with Magnet Pole Independence
Data Sheet 27622.61G
2 x 2 mm MLPD Package A3212EELLT-T
Approximate actual size
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VDD .............................. 5 V Magnetic Flux Density, B .......... Unlimited Output Off Voltage, VOUT ...................... 5 V Output Current, IOUT ........................... 1 mA Junction Temperature, TJ ................ +170C Operating Temperature, TA Range 'E-' .................... -40C to +85C Range 'L-' .................. -40C to +150C Storage Temperature Range, TS .............................. -65C to +170C
Caution: These CMOS devices have input static protection (Class 3) but are still susceptible to damage if exposed to extremely high static electrical charges.

A3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
Product Selection Guide
Use complete part numbers when ordering
Part Number A3212EEHLT A3212EEHLT-T A3212EELLT-T A3212ELHLT A3212ELHLT-T A3212EUA A3212EUA-T A3212LLHLT A3212LLHLT-T A3212LUA A3212LUA-T Pb-free - Yes Yes - Yes - Yes - Yes - Yes Packing* (Units/Pack) Tape and Reel (3000) Tape and Reel (3000) Tape and Reel (2000) Tape and Reel (3000) Tape and Reel (3000) Bulk Pack (500) Bulk Pack (500) Tape and Reel (3000) Tape and Reel (3000) Bulk Pack (500) Bulk Pack (500) 3-Pin Surface Mount SIP-3 Through Hole, Straight Lead 3-Pin Surface Mount -40 to 150 SIP-3 Through Hole, Straight Lead -40 to 85 Leadless Surface Mount Package Ambient Temperature TA (C)
*Contact Allegro for additional packaging and handling options.
FUNCTIONAL BLOCK DIAGRAM
SUPPLY
SWITCH
TIMING LOGIC
DYNAMIC OFFSET CANCELLATION
OUTPUT
SAMPLE & HOLD
LATCH
X
GROUND
Dwg. FH-020-5
2
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
Package Suffix `EH' Pinning
(Leadless Chip Carrier)
NO CONNECTION
Dwg. PH-016-2
Package Suffix `EL' Pinning
(Leadless Chip Carrier)
GROUND
SUPPLY
6 VDD
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.
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Copyright (c) 2002, 2003 Allegro MicroSystems, Inc.
OUTPUT
SUPPLY
OUTPUT
SUPPLY
3
A3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless otherwise specified).
Limits Characteristic Supply Voltage Range Output Leakage Current Output On Voltage Awake Time Period Duty Cycle Chopping Frequency Supply Current Symbol VDD IOFF VOUT tawake tperiod d.c. fC IDD(EN) IDD(DIS) IDD(AVG) Chip awake (enabled) Chip asleep (disabled) VDD = 2.75 V VDD = 3.5 V Test Conditions Operating1 VOUT = 3.5 V, BRPN < B < BRPS IOUT = 1 mA, VDD = 2.75 V 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 A mV s ms % kHz mA A A A
NOTES: 1. Operate and release points will vary with supply voltage. 2. BOPx = operate point (output turns on); BRPx = release point (output turns off). 3. Typical Data is at TA = +25C and VDD = 2.75 V and is for design information only.
MAGNETIC CHARACTERISTICS over operating voltage and temperature range (unless otherwise specified).
Limits Characteristic Operate Points Symbol BOPS BOPN Release Points BRPS BRPN Hysteresis Bhys Test Conditions South pole to branded side North pole to branded side South pole to branded side North pole to branded side |BOPx - BRPx| Min. - -55 10 - - Typ. 37 -40 31 -34 5.9 Max. 55 - - -10 - Units G G G G G
NOTES: 1. Negative flux densities are defined as less than zero (algebraic convention), i.e., -50 G is less than +10 G. 2. BOPx = operate point (output turns on); BRPx = release point (output turns off). 3. Typical Data is at TA = +25C and VDD = 2.75 V and is for design information only. 4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
4
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
TYPICAL OPERATING CHARACTERISTICS
SWITCH POINTS
60
60
40
BOPS BRPS
40
BOPS BRPS
SWITCH POINTS IN GAUSS
20
SWITCH POINTS IN GAUSS
20
0
VDD = 2.75 V
0
TA = 25C
-20 BRPN -40 BOPN
-20 BRPN -40 BOPN
-60 -50 -25 0 25 50 75 100 125 150
-60 2.4
2.6
2.8
3.0
3.2
3.4
3.6
Dwg. GH-057-2
AMBIENT TEMPERATURE IN C
Dwg. GH-027-3
SUPPLY VOLTAGE IN VOLTS
SUPPLY CURRENT
7.0
7.0
AVERAGE SUPPLY CURRENT IN A
6.0 VDD =3.5 V
AVERAGE SUPPLY CURRENT IN A
6.0
5.0
VDD =2.75 V
5.0
VDD =2.5 V 4.0
4.0
TA = 25C
3.0 -50
-25
0
25
50
75
100
125
150
3.0 2.4
2.6
2.8
3.0
3.2
3.4
3.6
Dwg. GH-058-7
AMBIENT TEMPERATURE IN C
Dwg. GH-028-11
SUPPLY VOLTAGE IN VOLTS
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A3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
FUNCTIONAL DESCRIPTION
Low Average Power. Internal timing circuitry activates the sensor for 45 s and deactivates it for the remainder of the period (45 ms). A short "awake" time allows for stabilization prior to the sensor sampling 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
B +V
--
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 dependencies, 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 Trackand-Hold Signal Demodulator.
HALL VOLTAGE
+
Dwg. AH-011-2
+V
SAMPLE & HOLD
X
Dwg. EH-012-1
6
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
FUNCTIONAL DESCRIPTION (cont'd)
Operation. The output of this device switches low (turns on) when a magnetic field perpendicular to the Hall sensor exceeds the operate point BOPS (or is less than BOPN). After turn-on, the output is capable of sinking up to 1 mA and the output voltage is VOUT(ON). When the magnetic field is reduced below the release point BRPS (or increased above BRPN), the device output switches high (turns off). 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. 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 capacitor be connected (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-stabilization technique. This is especially true due to the relatively high impedance of battery supplies. The simplest form of magnet that will operate these devices is a bar magnet with either pole near the branded surface of the device. Many other methods of operation are possible. Extensive applications information for Hall-effect sensors is available in: * Hall-Effect IC Applications Guide, Application Note 27701; * Hall-Effect Devices: Soldering, Gluing, Potting, Encapsulating, 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
OUTPUT 10 pF
3 2
5V MAX
OUTPUT OFF B OPN B OPS
OUTPUT VOLTAGE
BRPN 0 -B 0
BRPS
OUTPUT ON
+B
Dwg. GH-043-1
MAGNETIC FLUX
DD
50 k
V
1
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X
SUPPLY (3 V BATTERY) 0.1 F
Dwg. EH-013-2
7
A3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
SENSOR LOCATIONS
Package Designator 'EH'
ACTIVE AREA DEPTH 0.013" 0.34 mm NOM 6 5 0.035" 0.88 mm 4 0.062" 1.56 mm
Package Designator 'EL'
ACTIVE AREA DEPTH 0.006" 0.16 mm NOM 3 .0406 1.03 mm
.0291 0.74 mm
BRANDED SURFACE
A
1 2 3
Dwg. MH-030
BRANDED SURFACE
A
1 2
Package Designator 'LH'
ACTIVE AREA DEPTH 0.011" 0.28 mm NOM 0.056" 1.42 mm 3
Package Designator 'UA'
ACTIVE AREA DEPTH 0.0195" 0.50 mm NOM
0.033" 0.84 mm
0.078" 1.98 mm 0.052" 1.32 mm
A
1 2
Dwg. MH-025-2
A
BRANDED SURFACE 1 2 3
Dwg. MH-011-13
8
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
PACKAGE DESIGNATOR `EH'
(Reference MO-229C WCED-1)
2.15 .085 1.85 .073 6
3.15 .124 2.85 .112 A 1
0.50 .020 BSC 0.30 .012 BSC 1.00 .039 BSC 3.70 .146 BSC 1.25 .049 BSC 0.25 .010 BSC 1 0.25 .010 BSC 0.40 .016 BSC 0.95 .037 BSC C 6
0.30 .012 0.20 .008 0.50 .020 BSC 1 0.65 .026 0.45 .018 1.324 .052 1.074 .042 B
0.80 .031 0.70 .028 0.20 .008 REF 0.05 .002 0.00 .000
6 1.142 .045 0.892 .035
Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only A Pin index area B Exposed thermal pad C o0.3 Thermal via (optional)
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9
3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
PACKAGE DESIGNATOR `EL'
MLPD 3 Contact
2.00 .079 BSC 3
2.00 .079 BSC A 1 2
1.350 .053 BSC 0.325 .013 REF 0.32 .013 MIN 1.025 .040 MAX 0.20 .008 REF D C 0.138 .005 REF 3
0.32 .013 0.20 .008 0.50 .020 BSC 0.50 .020 0.30 .012
0.55 .022 0.45 .018 0.15 .006 REF 0.05 .002 0.80 .031 0.00 .000 0.70 .028 1 2 0.138 .005 REF
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]
R0.200 .008 REF B
1.025 .040 0.775 .031
0.15 .006 MIN 1 0.40 .016 NOM
2.40 .094 REF 1.350 .053 1.100 .043
D Typical pad layout; adjust as necessary to meet application process requirements
3
0.50 .020 BSC
0.325 .013 REF
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3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
PACKAGE DESIGNATOR `LH'
(SOT23W, fits SC-59A solder-pad layout)
Dimensions in Inches (for reference only)
0.122 0.114 0.020 0.012
0.083 0.073
3 1 2
Dimensions in Millimeters (controlling dimensions)
3.10 2.90
0.50 0.30
0.118 0.106
GAUGE PLANE SEATING PLANE
0.010
BSC
2.10 1.85
3
1 2
3.00 2.70
GAUGE PLANE SEATING PLANE
0.25
BSC
0.022
REF
0.55
0.010
MIN
0.037
BSC
0 TO 8
0.0079 0.0050
REF
0.95
BSC
0 TO 8
0.25
MIN
0.006 0.000
0.045 0.032
0.15 0.00
Dwg. MA-010-3D in
1.13 0.87
0.20 0.127
Dwg. MA-010-3D mm
0.028
3
3
0.70 1.00
0.039 0.094
1 2
2.40
1 2
0.037
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.
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A3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
PACKAGE DESIGNATOR `UA'
Dimensions in Inches (controlling dimensions)
0.164 0.159
Dimensions in Millimeters (for reference only)
4.17 4.04
45
0.062 0.058
45
1.57 1.47
0.122 0.117 45 0.031
3.10 2.97 45 0.79
0.085
MAX
1
2
3
2.16
MAX
1
2
3
0.640 0.600
0.0173 0.0138
16.26 15.24
0.44 0.35
SEE NOTE
0.0189 0.0142
SEE NOTE
0.48 0.36
0.050
BSC
Dwg. MH-014E in
1.27
BSC
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.
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3212 MICROPOWER, ULTRA-SENSITIVE HALL-EFFECT SWITCH
The products described herein are manufactured under one or more of the following U.S. patents: 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 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 products are not authorized for use as critical components in life-support appliances, devices, or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties that may result from its use.
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13
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