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LMT90
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SNIS177A – MARCH 2013 – REVISED AUGUST 2013
LMT90 SOT-23 Single-Supply Centigrade Temperature Sensor
FEATURES
DESCRIPTION
•
•
The LMT90 is a precision integrated-circuit
temperature sensor that can sense a −40°C to
+125°C temperature range using a single positive
supply. The LMT90's output voltage is linearly
proportional to Celsius (Centigrade) temperature (+10
mV/°C) and has a DC offset of +500 mV. The offset
allows reading negative temperatures without the
need for a negative supply. The ideal output voltage
of the LMT90 ranges from +100 mV to +1.75V for a
−40°C to +125°C temperature range. The LMT90
does not require any external calibration or trimming
to provide accuracies of ±3°C at room temperature
and ±4°C over the full −40°C to +125°C temperature
range. Trimming and calibration of the LMT90 at the
wafer level assure low cost and high accuracy. The
LMT90's linear output, +500 mV offset, and factory
calibration simplify circuitry required in a single supply
environment where reading negative temperatures is
required. The LMT90's quiescent current is less than
130 μA, thus self-heating is limited to a very low
0.2°C in still air.
1
2
•
•
•
•
•
•
•
•
•
Cost-Effective Alternative to Thermistors
Calibrated Directly in Degree Celsius
(Centigrade)
Linear + 10.0 mV/°C Scale Factor
±3°C Accuracy Guaranteed at +25°C
Specified for Full −40° to +125°C range
Suitable for Remote Applications
Low Cost Due to Wafer-level Trimming
Operates from 4.5V to 10V
Less than 130 μA Current Drain
Low Self-heating, Less than 0.2°C in Still Air
Nonlinearity Less than 0.8°C Over Temp
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
Industrial
HVAC
Disk Drives
Automotive
Portable Medical Instruments
Computers
Battery Management
Printers
Power Supply Modules
FAX Machines
The LMT90 is a cost-competitive alternative to
thermistors.
CONNECTION DIAGRAM
Figure 1. SOT-23 Top View
TYPICAL APPLICATION
+VS
(4.5 V to 10 V)
LMT90
Output
VOUT = (10 mV/°C u Temp °C) + 500 mV
VOUT = +1.750 V at +125°C
VOUT = +750 mV at +25°C
VOUT = +100 mV at -40°C
Figure 2. Full-Range Centigrade Temperature
Sensor (−40°C to +125°C)
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2013, Texas Instruments Incorporated
LMT90
SNIS177A – MARCH 2013 – REVISED AUGUST 2013
www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
VALUES
Supply Voltage
+12V to −0.2V
Output Voltage
(+VS + 0.6V) to −1.0V
Output Current
10 mA
−65°C to +150°C
Storage Temperature
TJMAX, Maximum Junction Temperature
ESD Susceptibility
(1)
(2)
(2)
150°C
Human Body Model
2000V
Machine Model
250V
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not
apply when operating the device beyond its rated operating conditions.
Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin.
OPERATING RATINGS
Specified Temperature Range:
TMIN to TMAX
−40°C to +125°C
LMT90
−40°C to +150°C
Operating Temperature Range
θJA (1)
450°C/W
Supply Voltage Range (+VS)
+4.5V to +10V
Soldering process must comply with the Reflow Temperature Profile specifications. Refer to www.ti.com/packaging. (2)
(1)
(2)
2
Thermal resistance of the SOT-23 package is specified without a heat sink, junction to ambient.
Reflow temperature profiles are different for lead-free and non-lead-free packages.
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ELECTRICAL CHARACTERISTICS
Unless otherwise noted, these specifications apply for VS = +5 VDC and ILOAD = +0.5 μA, in the circuit of Figure 2. Boldface
limits apply for the specified TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25°C, unless otherwise noted.
PARAMETER
Accuracy
(2)
Nonlinearity
MAX (1)
UNITS
(LIMIT)
TA = +25°C
±3.0
°C (max)
TA = TMAX
±4.0
°C (max)
TA = TMIN
±4.0
°C (max)
±0.8
°C (max)
CONDITIONS
TYPICAL
(3)
Sensor Gain
+9.7
mV/°C (min)
(Average Slope)
+10.3
mV/°C (max)
4000
Ω (max)
±0.8
mV/V (max)
±1.2
mV/V (max)
130
μA (max)
180
μA (max)
2.0
μA (max)
Output Resistance
Line Regulation
2000
(4)
Quiescent Current
+4.5V ≤ VS ≤ +10V
(5)
Change of Quiescent Current
+4.5V ≤ VS ≤ +10V
(5)
+4.5V ≤ VS ≤ +10V
Temperature Coefficient of Quiescent Current
Long Term Stability
(1)
(2)
(3)
(4)
(5)
(6)
(6)
TJ = 125°C, for 1000 hours
+2.0
μA/°C
±0.08
°C
Limits are specific to TI's AOQL (Average Outgoing Quality Level).
Accuracy is defined as the error between the output voltage and 10mv/°C times the device's case temperature plus 500 mV, at specified
conditions of voltage, current, and temperature (expressed in °C).
Nonlinearity is defined as the deviation of the output-voltage-versus-temperature curve from the best-fit straight line, over the device's
rated temperature range.
Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output due to heating
effects can be computed by multiplying the internal dissipation by the thermal resistance.
Quiescent current is defined in the circuit of Figure 2.
For best long-term stability, any precision circuit will give best results if the unit is aged at a warm temperature, and/or temperature
cycled for at least 46 hours before long-term life test begins. This is especially true when a small (Surface-Mount) part is wave-soldered;
allow time for stress relaxation to occur. The majority of the drift will occur in the first 1000 hours at elevated temperatures. The drift after
1000 hours will not continue at the first 1000 hour rate.
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LMT90
SNIS177A – MARCH 2013 – REVISED AUGUST 2013
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TYPICAL PERFORMANCE CHARACTERISTICS
To generate these curves the LMT90 was mounted to a printed circuit board as shown in Figure 14.
4
Thermal Resistance Junction to Air
Thermal Time Constant
Figure 3.
Figure 4.
Thermal Response in Still Air
with Heat Sink (Figure 14)
Thermal Response in Stirred Oil Bath
with Heat Sink
Figure 5.
Figure 6.
Start-Up Voltage
vs Temperature
Thermal Response in Still
Air without a Heat Sink
Figure 7.
Figure 8.
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SNIS177A – MARCH 2013 – REVISED AUGUST 2013
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
To generate these curves the LMT90 was mounted to a printed circuit board as shown in Figure 14.
Quiescent Current vs
Temperature (Figure 2)
Accuracy
vs
Temperature
Figure 9.
Figure 10.
Noise Voltage
Supply Voltage
vs Supply Current
Figure 11.
Figure 12.
Start-Up Response
Figure 13.
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LMT90
SNIS177A – MARCH 2013 – REVISED AUGUST 2013
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PRINTED CIRCUIT BOARD
A.
1/2″ Square Printed Circuit Board with 2 oz. Foil or Similar
Figure 14. Printed Circuit Board Used for Heat Sink to Generate All Curves
MOUNTING
The LMT90 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be
glued or cemented to a surface and its temperature will be within about 0.2°C of the surface temperature.
This presumes that the ambient air temperature is almost the same as the surface temperature; if the air
temperature were much higher or lower than the surface temperature, the actual temperature of the LMT90 die
would be at an intermediate temperature between the surface temperature and the air temperature.
To ensure good thermal conductivity the backside of the LMT90 die is directly attached to the GND pin. The
lands and traces to the LMT90 will, of course, be part of the printed circuit board, which is the object whose
temperature is being measured. These printed circuit board lands and traces will not cause the LMT90s
temperature to deviate from the desired temperature.
Alternatively, the LMT90 can be mounted inside a sealed-end metal tube, and can then be dipped into a bath or
screwed into a threaded hole in a tank. As with any IC, the LMT90 and accompanying wiring and circuits must be
kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold
temperatures where condensation can occur. Printed-circuit coatings and varnishes such as Humiseal and epoxy
paints or dips are often used to ensure that moisture cannot corrode the LMT90 or its connections.
Table 1. Temperature Rise of LMT90 Due to Self-Heating (Thermal Resistance, θJA)
Still air
SOT-23
no heat sink (1)
SOT-23
small heat fin (2)
450°C/W
260°C/W
Moving air
(1)
(2)
6
180°C/W
Part soldered to 30 gauge wire.
Heat sink used is 1/2″ square printed circuit board with 2 oz. foil with part attached as shown in Figure 14.
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SNIS177A – MARCH 2013 – REVISED AUGUST 2013
CAPACITIVE LOADS
+
LMT90
Heavy Capacitive Load, Wiring, Etc.
To A High-Impedance Load
OUT
d
Figure 15. LMT90 No Decoupling Required for Capacitive Load
+
LMT90
0.1 µF Bypass
Optional
d
Heavy Capacitive Load, Wiring, Etc.
OUT
1 µF
Figure 16. LMT90C with Filter for Noisy Environment
The LMT90 handles capacitive loading very well. Without any special precautions, the LMT90 can drive any
capacitive load. The LMT90 has a nominal 2 kΩ output impedance (as can be seen in Figure 17). The
temperature coefficient of the output resistors is around 1300 ppm/°C. Taking into account this temperature
coefficient and the initial tolerance of the resistors the output impedance of the LMT90 will not exceed 4 kΩ. In an
extremely noisy environment it may be necessary to add some filtering to minimize noise pickup. It is
recommended that 0.1 μF be added from VIN to GND to bypass the power supply voltage, as shown in
Figure 16. In a noisy environment it may be necessary to add a capacitor from the output to ground. A 1 μF
output capacitor with the 4 kΩ output impedance will form a 40 Hz lowpass filter. Since the thermal time constant
of the LMT90 is much slower than the 25 ms time constant formed by the RC, the overall response time of the
LMT90 will not be significantly affected. For much larger capacitors this additional time lag will increase the
overall response time of the LMT90.
*R2 ≈ 2k with a typical 1300 ppm/°C drift.
Figure 17. Block Diagram
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LMT90
SNIS177A – MARCH 2013 – REVISED AUGUST 2013
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TYPICAL APPLICATIONS
Figure 18. Centigrade Thermostat/Fan Controller
Figure 19. Temperature To Digital Converter (Serial Output) (+125°C Full Scale)
Figure 20. Temperature To Digital Converter (Parallel TRI-STATE Outputs for
Standard Data Bus to μP Interface) (125°C Full Scale)
8
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SNIS177A – MARCH 2013 – REVISED AUGUST 2013
Figure 21. LMT90 With Voltage-To-Frequency Converter And Isolated Output
(−40°C to +125°C; 100 Hz to 1750 Hz)
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PACKAGE OPTION ADDENDUM
www.ti.com
9-Aug-2013
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
(2)
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
LMT90DBZR
ACTIVE
SOT-23
DBZ
3
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
T8C
LMT90DBZT
ACTIVE
SOT-23
DBZ
3
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
T8C
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Samples
PACKAGE MATERIALS INFORMATION
www.ti.com
12-Aug-2013
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
LMT90DBZR
SOT-23
DBZ
3
3000
178.0
8.4
LMT90DBZT
SOT-23
DBZ
3
250
178.0
8.4
Pack Materials-Page 1
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
3.3
2.9
1.22
4.0
8.0
Q3
3.3
2.9
1.22
4.0
8.0
Q3
PACKAGE MATERIALS INFORMATION
www.ti.com
12-Aug-2013
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMT90DBZR
SOT-23
DBZ
3
3000
210.0
185.0
35.0
LMT90DBZT
SOT-23
DBZ
3
250
210.0
185.0
35.0
Pack Materials-Page 2
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