LM62
2.7V, 15.6 mV/°C SOT-23 Temperature Sensor

General Description

The LM62 is a precision integrated-circuit temperature sen-
sor that can sense a 0°C to +90°C temperature range while
operating from a single +3.0V supply. The LM62's output
voltage is linearly proportional to Celsius (Centigrade) tem-
perature (+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 temperature 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 ľA, 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 di-
rectly 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 ľA (max)

Nonlinearity

0.8°C (max)

Output Impedance

4.7 k

(max)

Connection Diagram

Ordering Information

Order

SOT-23

Number

Device

Supplied As

Marking

LM62BIM3

T7B

1000 Units on Tape and Reel

LM62BIM3X

T7B

3000 Units on Tape and Reel

LM62CIM3

T7C

1000 Units on Tape and Reel

LM62CIM3X

T7C

3000 Units on Tape and Reel

Typical Application

SOT-23

DS100893-1

Top View

See NS Package Number MA03B

DS100893-2

= (+15.6 mV/°C x T°C) + 480 mV

Temperature (T)

Typical V

+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

June 1999

LM62

2.7V

15.6

mV/°C,

SOT-23

emperature

Sensor

Š 1999 National Semiconductor Corporation

DS100893

www.national.com

Absolute Maximum Ratings

(Note 1)

Supply Voltage

+12V to -0.2V

Output Voltage

(+V

+ 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

Maximum Junction Temperature (T

JMAX

)

+125°C

ESD Susceptibility (Note 3) :

Human Body Model

2500V

Machine Model

250V

Lead Temperature:

SOT Package (Note 4) :

Vapor Phase (60 seconds)

+215°C

Infrared (15 seconds)

+220°C

Operating Ratings

(Note 1)

Specified Temperature Range:

MIN

MAX

LM62B, LM62C

0°C

+90°C

Supply Voltage Range (+V

)

+2.7V to +10V

Thermal Resistance,

(Note 5)

450°C/W

Electrical Characteristics

Unless otherwise noted, these specifications apply for +V

= +3.0 V

. Boldface limits apply for T

= T

MIN

to T

MAX

; all

other limits T

= T

= 25°C.

Parameter

Conditions

Typical

(Note 6)

LM62B

LM62C

Units

(Limit)

Limits

(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

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

+10V

4.7

(max)

0°C

+75°C, +V

= +2.7V

4.4

(max)

Line Regulation (Note 10)

+3.0V

+10V

1.13

mV/V (max)

+2.7V

+3.3V, 0°C

+75°C

9.7

mV (max)

Quiescent Current

+2.7V

+10V

130

ľA (max)

165

ľA (max)

Change of Quiescent Current

+2.7V

+10V

ľA

Temperature Coefficient of

0.2

ľA/°C

Quiescent Current

Long Term Stability (Note 11)

MAX

=+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 func-
tional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed speci-
fications 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 (V

) at any pin exceeds power supplies (V

GND or V

), 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 k

resistor into each pin. The machine model is a 200 pF capacitor discharged di-

rectly into each pin.

Note 4: See AN-450 "Surface Mounting Methods and Their Effect on Product Reliability" or the section titled "Surface Mount" found in any post 1986 National Semi-
conductor Linear Data Book for other methods of soldering surface mount devices.

Note 5: The junction to ambient thermal resistance (

) is specified without a heat sink in still air.

Note 6: Typicals are at T

= T

= 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 com-
puted 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 ma-
jority 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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Typical Performance Characteristics

To generate these curves the LM62 was mounted to a

printed circuit board as shown in

Figure 2. (Continued)

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 ac-
tual temperature measured would be at an intermediate tem-
perature between the surface temperature and the air tem-
perature.

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 cir-
cuit board, which is the object whose temperature is being
measured. These printed circuit board lands and traces will
not cause the LM62's temperature to deviate from the de-
sired 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 en-
sure that moisture cannot corrode the LM62 or its connec-
tions.

The thermal resistance junction to ambient (

) 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:

= T

[(+V

) + (+V

- V

) I

]

where I

is the quiescent current and I

is 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.

Supply Voltage
vs Supply Current

DS100893-12

Start-Up Response

DS100893-22

DS100893-14

FIGURE 2. Printed Circuit Board Used

for Heat Sink to Generate All Curves.

" Square Printed Circuit Board

with 2 oz. Copper Foil or Similar.

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1.0 Mounting

(Continued)

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.

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 k

. In an ex-

tremely noisy environment it may be necessary to add some
filtering to minimize noise pickup. It is recommended that

0.1 ľF be added from +V

to GND to bypass the power sup-

ply 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 ľF output capacitor with the 4.7 k

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 capacitors this additional time lag will increase the
overall response time of the LM62.

SOT-23

no heat sink

small heat fin

(Note 13)

(Note 12)

- T

(°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

" 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 (

)

DS100893-15

FIGURE 4. LM62 No Decoupling Required for

Capacitive Load

DS100893-16

FIGURE 5. LM62 with Filter for Noisy Environment

DS100893-17

FIGURE 6. Simplified Schematic

Part Number LM62