Datasheet
Magnetoresistive Sensor ICs
Nanopower Series
2sensing.honeywell.com
Magnetoresistive Sensor ICs
Honeywell’s Nanopower Series Magnetoresistive (MR) Sensor ICs are ultra-sensitive devices designed to accommodate a
wide range of applications with large air gaps, small magnetic fields and low power requirements.
The sensor ICs respond to either a North or South pole applied in a direction parallel to the sensor. They do not require the
magnet polarity to be identified, simplifying installation and potentially reducing system cost.
These sensor ICs use a very low average current consumption and a push-pull output which does not require a pull-up
resistor. The sensor ICs can operate from a supply voltage as low as 1.65 V, promoting energy efficiency.
The Nanopower Series is available in two magnetic sensitivities to accommodate a variety of application needs:
• SM 351LT: For applications requiring ultra high magnetic sensitivity (7 G typical operate, 11 G maximum operate) and a
very low current draw (360 nA typical).
• SM353LT: For applications requiring very high magnetic sensitivity (14 G typical operate, 20 G maximum operate) and
a very low current draw (310 nA typical).
These Magnetoresistive Sensor ICs, Nanopower Series, are supplied in the subminiature SOT-23 surface mount package
on tape and reel (3000 units per reel), for use in automated pick-and-place component installation.
HIGH SENSITIVITy • NANOPOWEr
Key Features
• High sensitivity: 7 Gauss typ., 11 Gauss max. (SM351LT);
14 G typ., 20 Gauss max. (SM353LT)
• Nanopower: Average current of 360 nA typ. (SM351LT) and
310 nA typ. (SM353LT)
• Supply voltage range: 1.65 Vdc to 5.5 Vdc; simplifies
design-in
• Omnipolar sensing: Activates with either pole from a
magnet
• Temperature range: -40 °C to 85 °C [-40 °F to 185 °F]
• Push-pull output: Does not require external pull-up resistor
• Non-chopper stabilized design
• RoHS-compliant materials: Meets Directive 2002/95/EC
• Package: SOT-23
Potential Applications
INDUSTRIAL
• Mobile equipment (i.e., handheld computing equipment,
scanners)
• Water,electricandgasutilitymeters
• Buildingaccesscontrol;reedswitchreplacementforbattery-
operated security systems
• Industrialsmokedetectors
MEDICAL
• Exerciseequipment
• Infusionpumps
• Drawerpositionsensing(e.g.,medicalcabinets)
• Hospitalbeds
WHITE GOODS
• Lid,dooranddrawerpositiondetection
• Fluidow
MEDIUM-SIZED CONSUMER ELECTRONICS
• Battery-optimizationpositionsensor
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Magnetoresistive Sensor ICs, Nanopower Series
HIGH SENSITIVITy • NANOPOWEr
Table 1A. Electrical Specifications (Vs = 1.65 V to 5.5 V, Ta = -40 °C to 85 °C [-40 °F to 185 °F], Typ. at 1.8 V, 25 °C [77 °F] unless otherwise specified.)
Characteristic Condition Min. Typ. Max. Unit
Supply voltage (Vs) Vs reference to ground 1.65 1.8 5.5 V
Awake current:
SM351LT
SM353LT
— —
0.3
1
0.8
5
5
mA
Awake time — — 15 —µs
Sleep current
—
Vs = 1.65 V
Vs = 1.8 V
Vs = 5.5 Vdc
—
—
—
—
0.2
0.16
0.2
2.6
8
0.8
1
8
µA
Sleep time —30 100 180 ms
Average current:
SM351LT
SM353LT
0.015% duty cycle, typ. —
—
360
310
6640
6350
nA
Output voltage:
low (VOL)
high (VOH)
load current = 100 µA 0
Vs - 0.15
0.03
Vs - 0.03
0.15
Vs
V
NOTICE
ThesensorwillturnLOWwhenthemagneticeldispresentand
switchtoHIGHwhentheeldisremoved.Thesensorwilllatchand
hold the state during the sleep “mode”.
NOTICE
These magnetoresistive sensor ICs may have an initial output in
either the ON or OFF state if powered up with an applied magnetic
eldinthedifferentialzone(appliedmagneticeld>Brpand<Bop).
Honeywellrecommendsallowing10μsforoutputvoltagetostabilize
aftersupplyvoltagehasreacheditsnalratedvalue.
Table 1B. Electrical Specifications (Vs = 1.8 V, Ta = 25 °C [77 °F].)
Characteristic Condition Min. Typ. Max. Unit
Awake current:
SM351LT
SM353LT
— —
—
1
0.8
1.12
0.87
mA
Awake time — — 15 —µs
Sleep current — — 0.2 0.59 µA
Sleep time —90 100 120 ms
Average current:
SM351LT
SM353LT
0.015% duty cycle, typ. —
—
350
350
620
600
nA
Magnetoresistive Sensor ICs, Nanopower Series
4sensing.honeywell.com
NOTICE
Absolute maximum ratings are the extreme limits that the device will withstand without damage to the device.
However, the electrical and mechanical characteristics are not guaranteed as the maximum limits (above
recommended operating conditions) are approached, nor will the device necessarily operate at absolute
maximum ratings.
CAUTION
ELECTROSTATIC
SENSITIVE
DEVICES
DO NOT OPEN OR HANDLE
EXCEPT AT A
STAT IC FREE WORKSTAT ION
ESD SENSITIVITY:
CLASS 2
Table 3. Absolute Maximum Ratings
Characteristic Condition Min. Typ. Max. Unit
Operating temperature ambient -40 [-40] —85 [185] °C [°F]
Soldering temperature ambientappliedfor<10s — — 265 [509] °C [°F]
Supply voltage (Vs) —-0.5 — 6 V
Output (load) current — — — 5mA
Figure 1. Block/Electrical Diagram
NOTICE
Themagneticeldstrength(Gauss)requiredtocausetheswitchto
changestate(operateandrelease)willbeasspeciedinthemagnetic
characteristics.Totesttheswitchagainstthespeciedmagnetic
characteristics,theswitchmustbeplacedinauniformmagneticeld.
Output
Flip
Flop
Clock
Counter
Decoder
AMR
VS+
Gnd-
Dual
Threshold
Comparator
Out
DQ
0
V
Table 2. Magnetic Specifications (Vs = 1.65 V to 5.5 V, Ta = -40 °C to 85 °C [-40 °F to 185 °F].)
Characteristic Min. Typ. Max. Unit
SM3 51LT:
operate (positive)
release (positive)
hysteresis
3
2
*
7
5
2
11
—
—
Gauss
SM353LT:
operate (positive)
release (positive)
hysteresis
6
3
*
14
10
4
20
—
—
Gauss
*At 1.65 V and -40 °C, the hysteresis can reach 0.1 Gauss.
5
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Magnetoresistive Sensor ICs, Nanopower Series
Figure 2. Alignment of the Magnet to the Omnipolar Magnetoresistive Sensor IC
Ideal alignment: The magnet is aligned in the same plane as the sensor IC.
Offset alignment: The magnet is not aligned in the same plane as the sensor IC.
SM351LT,
SM353LT
Sensor IC
Magnet
Magnet movement
Magnet
SM351LT,
SM353LT
Sensor IC
Magnet movement
Magnet
Magnet
SM351LT,
SM353LT
Sensor IC
Magnet movement
end view
top view
ThesensorICdetectstheapproachingmagnet’shorizontalmagneticuxlines,turningthesensorICtoON.ThesensorICstaysONasthe
magnetcontinuestoapproach.WhenthemagnetislocateddirectlyoverthesensorIC,allmagneticuxlinesarenowhorizontal(seeFigure
2.C).(Note:ThisalignmentdecreasesthemagneticuxstrengthatthesensorIC.)
Themagneticuxlinesstayhorizontalasthemagnetapproachesthe
sensor IC (see Figure 2.A).
Deadzonesmayoccurwhenthemajorityofthemagnet’smagnetic
uxlinesbecomeverticalasitapproachesthesensorIC,turning
thesensorICtoON,thenOFF,thenON(seeFigure2.B).
Perpendicular magnet approach to the sensor IC eliminates possible dead zones.
Parallel magnet approach to the sensor IC may cause dead zones.
Figure 2.A
Figure 2.B
Figure 2.C
Magnetoresistive Sensor ICs, Nanopower Series
6sensing.honeywell.com
0
2
4
6
8
10
12
-40-20 020406
08
0
Release Point
Temperature (°C)
Magnetic Switch Point (Gauss)
Operate Point
Figure 3. SM351LT Typical Performance Characteristics
Magnetic Performance vs Temperature (Vs = 1.8 V) Period vs Temperature
Average Current vs Temperature Active Mode Time vs Temperature
Temperature (°C)
Time (ms)
1.80 Vdc Supply
1.65 Vdc Supply
5.50 Vdc Supply
0
20
40
60
80
100
120
140
160
180
-40-20 020406080
Temperature (°C)
Average Current (µA)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-40-20 020406
08
0
1.80 Vdc Supply
1.65 Vdc Supply
5.50 Vdc Supply
Temperature (°C)
Time (µs)
1.80 Vdc Supply
1.65 Vdc Supply
5.50 Vdc Supply
0
5
10
15
20
25
-40-20 020406
08
0
Figure 4. SM353LT Typical Performance Characteristics
Magnetic Performance vs Temperature (Vs = 1.8 V) Period vs Temperature
Average Current vs Temperature Active Mode Time vs Temperature
0
2
4
6
8
10
12
14
16
18
20
-40-20 020406
08
0
Temperature (°C)
Magnetic Switch Point (Gauss)
Operate Point
Release Point
Temperature (°C)
Time (ms)
1.80 Vdc Supply
1.65 Vdc Supply
5.50 Vdc Supply
0
20
40
60
80
100
120
140
160
-40-20 020406
08
0
Temperature (°C)
Average Current (µA)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-40-20 020406
08
0
1.80 Vdc Supply
1.65 Vdc Supply
5.50 Vdc Supply
Temperature (°C)
Time (µs)
1.80 Vdc Supply
1.65 Vdc Supply
5.50 Vdc Supply
0
5
10
15
20
25
-40-20 020406
08
0
7
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Magnetoresistive Sensor ICs, Nanopower Series
Figure 5. Mounting and Tape/Reel Dimensions (For reference only. mm/[in].) E
7sensing.honeywell.com
3
GND
(-)
2,90
[0.114]
1
VCC
(+)
2
OUTPUT
1,40 Max.
[0.055]
1,20
[0.047]
0,77
[0.030]
0,60
[0.024]
0,787
[0.031]
0,413
[0.016]
1,90
[0.075]
0,95
[0.037]
3X 0,40 TYP.
[0.016]
2,80
[0.110]1,60
[0.063]
Nominal to IC
sensing
surface
Nominal to IC
center
61
61
or
0,13
[0.005]
0,20
[0.008]
1,40
[0.055]
0,061
[0.002]
3,15
[0.124]
3,20
[0.125]
1,50
[0.059]
2,00
[0.079]
4,00
[0.157]
4,00
[0.157]
8,00
[0.315]
1,75
[0.069]
3,50
[0.138]
1,00
[0.039]
To p
cover
tape
60,0
[2.362]
[0.429]
14,4
[0.567]
8,40
[0.331]
40,0
[1.57]
4,00
[0.157]
10
[0.394]
20,2
[0.795]
2,0
[0.079]
13,0
[0.512]
178
[7.000]
Measured at
hub
Measured at
hub
Measured at
outer edge
Min.
Max.
Reel
Tape
Sensor Sensor Showing Polarity
Sensing and Control
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1985 Douglas Drive North
Golden Valley, MN 55422
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50095501-C-EN IL50
April 2015
© 2015 Honeywell International Inc. All rights reserved.
Table 4. Order Guide
Catalog Listing Description
SM351LT Magnetoresistive sensor IC, high sensitivity (7 G typ.), nanopower, SOT-23 package,
tape and reel packaging (3000 units per reel)
SM353LT Magnetoresistive sensor IC, high sensitivity (14 G typ.), nanopower, SOT-23 package,
tape and reel packaging (3000 units per reel)
ADDITIONAL INFORMATION
The following associated literature is available at sensing.honeywell.com:
•Product line guide
•Product range guide
•Product installation instructions
•Applicationnote
WARRANTY/REMEDY
Honeywell warrants goods of its manufacture as being free of
defective materials and faulty workmanship. Honeywell’s standard
product warranty applies unless agreed to otherwise by Honeywell
in writing; please refer to your order acknowledgement or consult
your local sales office for specific warranty details. If warranted
goods are returned to Honeywell during the period of coverage,
Honeywell will repair or replace, at its option, without charge
those items it finds defective. The foregoing is buyer’s sole
remedy and is in lieu of all other warranties, expressed or
implied, including those of merchantability and fitness for
a particular purpose. In no event shall Honeywell be liable
for consequential, special, or indirect damages.
Whileweprovideapplicationassistancepersonally,throughour
literature and the Honeywell website, it is up to the customer to
determine the suitability of the product in the application.
Specifications may change without notice. The information we
supply is believed to be accurate and reliable as of this printing.
However, we assume no responsibility for its use.
WARNING
PERSONAL INJURY
DO NOT USE these products as safety or emergency stop
devices or in any other application where failure of the product
couldresultinpersonalinjury.
Failure to comply with these instructions could result in
death or serious injury.
WARNING
MISUSE OF DOCUMENTATION
• Theinformationpresentedinthisdatasheetisforreference
only. Do not use this document as a product installation
guide.
• Completeinstallation,operation,andmaintenance
information is provided in the instructions supplied with each
product.
Failure to comply with these instructions could result in
death or serious injury.
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