Rainbow Electronics LM45 - Manual

LM45
SOT-23 Precision Centigrade Temperature Sensors
General Description
The LM45 series are precision integrated-circuit temperature
sensors, whose output voltage is linearly proportional to the
Celsius (Centigrade) temperature. The LM45 does not re-
quire any external calibration or trimming to provide accura-
cies of
± 2˚C at room temperature and ± 3˚C over a full −20 to
+100˚C temperature range. Low cost is assured by trimming
and calibration at the wafer level. The LM45’s low output im-
pedance, linear output, and precise inherent calibration
make interfacing to readout or control circuitry especially
easy. It can be used with a single power supply, or with plus
and minus supplies. As it draws only 120 µA from its supply,
it has very low self-heating, less than 0.2˚C in still air. The
LM45 is rated to operate over a −20˚ to +100˚C temperature
range.
Applications
n Battery Management
n FAX Machines
n Printers
n Portable Medical Instruments
n HVAC
n Power Supply Modules
n Disk Drives
n Computers
n Automotive
Features
n Calibrated directly in ˚ Celsius (Centigrade)
n Linear + 10.0 mV/˚C scale factor
n
± 3˚C accuracy guaranteed
n Rated for full −20˚ to +100˚C range
n Suitable for remote applications
n Low cost due to wafer-level trimming
n Operates from 4.0V to 10V
n Less than 120 µA current drain
n Low self-heating, 0.20˚C in still air
n Nonlinearity only ± 0.8˚C max over temp
n Low impedance output, 20 Ω for 1 mA load
Connection Diagram
SOT-23
Order Device
Number Marking Supplied As
LM45BIM3 T4B 1000 Units on Tape and Reel
LM45BIM3X T4B 3000 Units on Tape and Reel
LM45CIM3 T4C 1000 Units on Tape and Reel
LM45CIM3X T4C 3000 Units on Tape and Reel
Typical Applications
SOT-23
DS011754-1
Top View
See NS Package Number MA03B
DS011754-3
FIGURE 1. Basic Centigrade Temperature
Sensor (+2.5˚C to +100˚C)
DS011754-4
Choose R
1
= −V
S
/50 µA
V
OUT
= (10 mV/˚C x Temp ˚C)
V
OUT
= +1,000 mV at +100˚C
= +250 mV at +25˚C
= −200 mV at −20˚C
FIGURE 2. Full-Range Centigrade
Temperature Sensor (−20˚C to +100˚C)
August 1999
LM45
SOT
-23
Precision
Centigrade
T
emperature
Sensors
© 2000 National Semiconductor Corporation DS011754 www.national.com