LM35

Precision Centigrade Temperature Sensors

General Description

The LM35 series are precision integrated-circuit temperature

sensors, whose output voltage is linearly proportional to the

Celsius (Centigrade) temperature. The LM35 thus has an

advantage over linear temperature sensors calibrated in

˚ Kelvin, as the user is not required to subtract a large

constant voltage from its output to obtain convenient Centi-

grade scaling. The LM35 does not require any external

temperature range. Low cost is assured by trimming and

calibration at the wafer level. The LM35’s low output imped-

ance, linear output, and precise inherent calibration make

interfacing to readout or control circuitry especially easy. It

can be used with single power supplies, or with plus and

minus supplies. As it draws only 60 µA from its supply, it has

very low self-heating, less than 0.1˚C in still air. The LM35 is

rated to operate over a −55˚ to +150˚C temperature range,

while the LM35C is rated for a −40˚ to +110˚C range (−10˚

with improved accuracy). The LM35 series is available pack-

aged in hermetic TO-46 transistor packages, while the

LM35C, LM35CA, and LM35D are also available in the

plastic TO-92 transistor package. The LM35D is also avail-

able in an 8-lead surface mount small outline package and a

plastic TO-220 package.

Features

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Calibrated directly in ˚ Celsius (Centigrade)

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Linear + 10.0 mV/˚C scale factor

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0.5˚C accuracy guaranteeable (at +25˚C)

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Rated for full −55˚ to +150˚C range

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Suitable for remote applications

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Low cost due to wafer-level trimming

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Operates from 4 to 30 volts

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Less than 60 µA current drain

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Low self-heating, 0.08˚C in still air

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Low impedance output, 0.1

Ω for 1 mA load

Typical Applications

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FIGURE 1. Basic Centigrade Temperature Sensor

(+2˚C to +150˚C)

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= +250 mV at +25˚C

= −550 mV at −55˚C

FIGURE 2. Full-Range Centigrade Temperature Sensor

November 2000

© 2000 National Semiconductor Corporation

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