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
calibration or trimming to provide typical accuracies of
±
1
⁄
4
˚C
at room temperature and
±
3
⁄
4
˚C over a full −55 to +150˚C
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
n Calibrated directly in ˚ Celsius (Centigrade)
n Linear + 10.0 mV/˚C scale factor
n 0.5˚C accuracy guaranteeable (at +25˚C)
n Rated for full −55˚ to +150˚C range
n Suitable for remote applications
n Low cost due to wafer-level trimming
n Operates from 4 to 30 volts
n Less than 60 µA current drain
n Low self-heating, 0.08˚C in still air
n Nonlinearity only
±
1
⁄
4
˚C typical
n Low impedance output, 0.1 Ω for 1 mA load
Typical Applications
DS005516-3
FIGURE 1. Basic Centigrade Temperature Sensor
(+2˚C to +150˚C)
DS005516-4
Choose R
1
=−V
S
/50 µA
V
OUT
=+1,500 mV at +150˚C
= +250 mV at +25˚C
= −550 mV at −55˚C
FIGURE 2. Full-Range Centigrade Temperature Sensor
November 2000
LM35 Precision Centigrade Temperature Sensors
© 2000 National Semiconductor Corporation DS005516 www.national.com
