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PDF LM45 Data sheet ( Hoja de datos )
| Número de pieza | LM45 | |
| Descripción | SOT-23 Precision Centigrade Temperature Sensors | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LM45 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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July 1999
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, 20Ω for 1 mA load
Connection Diagram
SOT-23
DS011754-1
Top View
See NS Package Number MA03B
Typical Applications
Order
Number
LM45BIM3
LM45BIM3X
LM45CIM3
LM45CIM3X
SOT-23
Device
Marking
T4B
T4B
T4C
T4C
Supplied As
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
DS011754-3
FIGURE 1. Basic Centigrade Temperature
Sensor (+2.5˚C to +100˚C)
© 1999 National Semiconductor Corporation DS011754
DS011754-4
Choose R1 = −VS/50 µA
VOUT= (10 mV/˚C x Temp ˚C)
VOUT = +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)
www.national.com
1 page  
Typical Applications
CAPACITIVE LOADS
Like most micropower circuits, the LM45 has a limited ability
to drive heavy capacitive loads. The LM45 by itself is able to
drive 500 pF without special precautions. If heavier loads are
anticipated, it is easy to isolate or decouple the load with a
resistor; see Figure 4. Or you can improve the tolerance of
capacitance with a series R-C damper from output to
ground; see Figure 5.
Any linear circuit connected to wires in a hostile environment
can have its performance affected adversely by intense elec-
tromagnetic sources such as relays, radio transmitters, mo-
tors with arcing brushes, SCR transients, etc, as its wiring
can act as a receiving antenna and its internal junctions can
act as rectifiers. For best results in such cases, a bypass ca-
pacitor from VIN to ground and a series R-C damper such as
75Ω in series with 0.2 or 1 µF from output to ground, as
shown in Figure 5, are often useful.
DS011754-14
FIGURE 7. 4-to-20 mA Current Source (0˚C to +100˚C)
DS011754-8
FIGURE 4. LM45 with Decoupling from Capacitive Load
FIGURE 5. LM45 with R-C Damper
DS011754-9
DS011754-15
FIGURE 8. Fahrenheit Thermometer
DS011754-12
FIGURE 6. Temperature Sensor,
Single Supply, −20˚C to +100˚C
DS011754-16
FIGURE 9. Centigrade Thermometer (Analog Meter)
5 www.national.com
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet LM45.PDF ] | |
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