LM62
LM6 2 2.7V, 15.6 mV/C SOT-23 Temperature Sensor
Literature Number: SNIS105D
LM62
February 8, 2010
2.7V, 15.6 mV/°C SOT-23 Temperature Sensor
General Description
The LM62 is a precision integrated-circuit temperature sensor
that can sense a 0°C to +90°C temperature range while op-
erating from a single +3.0V supply. The LM62's output voltage
is linearly proportional to Celsius (Centigrade) temperature
(+15.6 mV/°C) and has a DC offset of +480 mV. The offset
allows reading temperatures down to 0°C without the need for
a negative supply. The nominal output voltage of the LM62
ranges from +480 mV to +1884 mV for a 0°C to +90°C tem-
perature range. The LM62 is calibrated to provide accuracies
of ±2.0°C at room temperature and +2.5°C/−2.0°C over the
full 0°C to +90°C temperature range.
The LM62's linear output, +480 mV offset, and factory cali-
bration simplify external circuitry required in a single supply
environment where reading temperatures down to 0°C is re-
quired. Because the LM62's quiescent current is less than
130 μA, self-heating is limited to a very low 0.2°C in still air.
Shutdown capability for the LM62 is intrinsic because its in-
herent low power consumption allows it to be powered directly
from the output of many logic gates.
Features
Calibrated linear scale factor of +15.6 mV/°C
Rated for full 0°C to +90°C range with 3.0V supply
Suitable for remote applications
Applications
Cellular Phones
Computers
Power Supply Modules
Battery Management
FAX Machines
Printers
HVAC
Disk Drives
Appliances
Key Specifications
Accuracy at 25°C ±2.0 or ±3.0°C (max)
Temperature Slope +15.6 mV/°C
Power Supply Voltage Range +2.7V to +10V
Current Drain @ 25°C 130 μA (max)
Nonlinearity ±0.8°C (max)
Output Impedance 4.7 kΩ (max)
Connection Diagram
SOT-23
10089301
Top View
See NS Package Number mf03a
Ordering Information
Order Device
Number Top Mark Supplied As
LM62BIM3 T7B 1000 Units, Tape and Reel
LM62BIM3X T7B 3000 Units, Tape and Reel
LM62CIM3 T7C 1000 Units, Tape and Reel
LM62CIM3X T7C 3000 Units, Tape and Reel
Typical Application
10089302
VO = (+15.6 mV/°C × T°C) + 480 mV
Temperature (T) Typical VO
+90°C +1884 mV
+70°C +1572 mV
+25°C 870 mV
0°C +480 mV
FIGURE 1. Full-Range Centigrade Temperature Sensor
(0°C to +90°C)
Stabilizing a Crystal Oscillator
© 2010 National Semiconductor Corporation 100893 www.national.com
LM62 2.7V, 15.6 mV/°C, SOT-23 Temperature Sensor
Absolute Maximum Ratings (Note 1)
Supply Voltage +12V to −0.2V
Output Voltage (+VS + 0.6V) to −0.6V
Output Current 10 mA
Input Current at any pin (Note 2) 5 mA
Storage Temperature −65°C to +150°C
Junction Temperature, max
(TJMAX)+125°C
ESD Susceptibility (Note 3) :
Human Body Model 2500V
Machine Model 250V
Operating Ratings (Note 1)
Specified Temperature Range: TMIN TA TMAX
LM62B, LM62C 0°C TA +90°C
Supply Voltage Range (+VS)+2.7V to +10V
Thermal Resistance, θJA(Note 5)450°C/W
Soldering process must comply with National
Semiconductor's Reflow Temperature Profile specifications.
Refer to www.national.com/packaging. (Note 4)
Electrical Characteristics
Unless otherwise noted, these specifications apply for +VS = +3.0 VDC. Boldface limits apply for TA = TJ = TMIN to TMAX ; all other
limits TA = TJ = 25°C.
Parameter Conditions Typical
(Note 6)
LM62B LM62C Units
(Limit)
Limits Limits
(Note 7) (Note 7)
Accuracy (Note 8) ±2.0 ±3.0 °C (max)
+2.5/−2.0 +4.0/−3.0 °C (max)
Output Voltage at 0°C +480 mV
Nonlinearity (Note 9) ±0.8 ±1.0 °C (max)
Sensor Gain +16 +16.1 +16.3 mV/°C (max)
(Average Slope) +15.1 +14.9 mV/°C (min)
Output Impedance +3.0V +VS +10V 4.7 4.7 kΩ (max)
0°C TA +75°C, +VS= +2.7V 4.4 4.4 kΩ (max)
Line Regulation (Note 10)+3.0V +VS +10V ±1.13 ±1.13 mV/V (max)
+2.7V +VS +3.3V, 0°C TA +75°C ±9.7 ±9.7 mV (max)
Quiescent Current +2.7V +VS +10V 82 130 130 μA (max)
165 165 μA (max)
Change of Quiescent Current +2.7V +VS +10V ±5 μA
Temperature Coefficient of 0.2 μA/°C
Quiescent Current
Long Term Stability (Note 11) TJ=TMAX=+100°C,
for 1000 hours ±0.2 °C
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: When the input voltage (VI) at any pin exceeds power supplies (VI < GND or VI > +VS), the current at that pin should be limited to 5 mA.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
Note 4: Reflow temperature profiles are different for lead-free and non-lead-free packages.
Note 5: The junction to ambient thermal resistance (θJA) is specified without a heat sink in still air.
Note 6: Typicals are at TJ = TA = 25°C and represent most likely parametric norm.
Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 8: Accuracy is defined as the error between the output voltage and +15.6 mV/°C times the device's case temperature plus 480 mV, at specified conditions
of voltage, current, and temperature (expressed in °C).
Note 9: 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.
Note 10: 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.
Note 11: 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.
www.national.com 2
LM62
Typical Performance Characteristics To generate these curves the LM62 was mounted to a printed
circuit board as shown in Figure 2.
Thermal Resistance
Junction to Air
10089303
Thermal Time Constant
10089304
Thermal Response in
Still Air with Heat Sink
10089305
Thermal Response
in Stirred Oil Bath
with Heat Sink
10089306
Thermal Response in Still
Air without a Heat Sink
10089308
Quiescent Current
vs. Temperature
10089309
3 www.national.com
LM62
Accuracy vs Temperature
10089310
Noise Voltage
10089311
Supply Voltage
vs Supply Current
10089312
Start-Up Response
10089322
Circuit Board
10089314
FIGURE 2. Printed Circuit Board Used for Heat Sink to Generate All Curves. ½″ Square Printed Circuit Board with 2 oz.
Copper Foil or Similar.
www.national.com 4
LM62
1.0 Mounting
The LM62 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or ce-
mented to a surface. The temperature that the LM62 is sens-
ing will be within about +0.2°C of the surface temperature that
LM62's leads are attached to.
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 measured would be at an intermediate temper-
ature between the surface temperature and the air tempera-
ture.
To ensure good thermal conductivity the backside of the
LM62 die is directly attached to the GND pin. The lands and
traces to the LM62 will, of course, be part of the printed circuit
board, which is the object whose temperature is being mea-
sured. These printed circuit board lands and traces will not
cause the LM62's temperature to deviate from the desired
temperature.
Alternatively, the LM62 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 LM62 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 conden-
sation 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 LM62 or its connections.
The thermal resistance junction to ambient (θJA) is the pa-
rameter used to calculate the rise of a device junction tem-
perature due to its power dissipation. For the LM62 the
equation used to calculate the rise in the die temperature is
as follows:
TJ = TA + θJA [(+VS IQ) + (+VS − VO) IL]
where IQ is the quiescent current and ILis the load current on
the output. Since the LM62's junction temperature is the ac-
tual temperature being measured care should be taken to
minimize the load current that the LM62 is required to drive.
The table shown in Figure 3 summarizes the rise in die tem-
perature of the LM62 without any loading, and the thermal
resistance for different conditions.
SOT-23 SOT-23
no heat sink small heat fin
(Note 13) (Note 12)
θJA TJ − TAθJA TJ − TA
(°C/W) (°C) (°C/W) (°C)
Still air 450 0.17 260 0.1
Moving air 180 0.07
Note 12: Heat sink used is ½″ square printed circuit board with 2 oz. foil with
part attached as shown in Figure 2 .
Note 13: Part soldered to 30 gauge wire.
FIGURE 3. Temperature Rise of LM62 Due to
Self-Heating and Thermal Resistance (θJA)
2.0 Capacitive Loads
The LM62 handles capacitive loading well. Without any spe-
cial precautions, the LM62 can drive any capacitive load as
shown in Figure 4. Over the specified temperature range the
LM62 has a maximum output impedance of 4.7 kΩ. In an ex-
tremely noisy environment it may be necessary to add some
filtering to minimize noise pickup. It is recommended that
0.1 μF be added from +VS to GND to bypass the power supply
voltage, as shown in Figure 5. In a noisy environment it may
be necessary to add a capacitor from the output to ground. A
1 μF output capacitor with the 4.7 kΩ maximum output
impedance will form a 34 Hz lowpass filter. Since the thermal
time constant of the LM62 is much slower than the 30 ms time
constant formed by the RC, the overall response time of the
LM62 will not be significantly affected. For much larger ca-
pacitors this additional time lag will increase the overall re-
sponse time of the LM62.
10089315
FIGURE 4. LM62 No Decoupling Required for Capacitive
Load
10089316
FIGURE 5. LM62 with Filter for Noisy Environment
5 www.national.com
LM62
10089317
FIGURE 6. Simplified Schematic
3.0 Applications Circuits
10089318
FIGURE 7. Centigrade Thermostat
10089319
FIGURE 8. Conserving Power Dissipation with Shutdown
www.national.com 6
LM62
Physical Dimensions inches (millimeters) unless otherwise noted
SOT-23 Molded Small Outline Transistor Package (M3)
Order Number LM62BIM3 or LM62CIM3
NS Package Number mf03a
7 www.national.com
LM62
Notes
LM62 2.7V, 15.6 mV/°C, SOT-23 Temperature Sensor
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