National Semiconductor LM45B, LM45C Technical data
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LM45B/LM45C
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 require any external calibration or trimming to provide accura-
±
cies of
2˚C at room temperatureand±3˚C over a full−20to
+100˚C temperature range. Low cost is assured by trimming
and calibration at the wafer level. The LM45’s low output impedance, 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
n Low impedance output, 20Ω for 1 mA load
±
0.8˚C max over temp
LM45B/LM45C SOT-23 Precision Centigrade Temperature Sensors
January 1999
Connection Diagram
SOT-23
Top View
See NS Package Number MA03B
Typical Applications
FIGURE 1. Basic Centigrade Temperature
Sensor (+2.5˚C to +100˚C)
DS011754-1
DS011754-3
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
=
Choose R
=
V
OUT
V
OUT
/50 µA
−V
1
S
(10 mV/˚C x Temp ˚C)
=
+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)
DS011754-4
© 1999 National Semiconductor Corporation DS011754 www.national.com
Absolute Maximum Ratings (Note 1)
Supply Voltage +12V to −0.2V
Output Voltage +V
Output Current 10 mA
Storage Temperature −65˚C to +150˚C
Lead Temperature:
SOT Package (Note 2):
+ 0.6V to −1.0V
S
Operating Ratings (Note 1)
Specified Temperature Range
(Note 4) T
LM45B, LM45C −20˚C to +100˚C
Operating Temperature Range
LM45B, LM45C −40˚C to +125˚C
Supply Voltage Range (+V
) +4.0V to +10V
S
MIN
to T
MAX
Vapor Phase (60 seconds) 215˚C
Infrared (15 seconds) 220˚C
ESD Susceptibility (Note 3):
Human Body Model
Machine Model
2000V
250V
Electrical Characteristics
Unless otherwise noted, these specifications apply for +V
specifications also apply from +2.5˚C to T
to T
T
MIN
; all other limits T
MAX
=
T
A
in the circuit of
MAX
=
+25˚C, unless otherwise noted.
J
=
+5Vdc and I
S
Figure 1
Parameter Conditions LM45B LM45C Units
Typical Limit Typical Limit
=
Accuracy T
(Note 6) T
Nonlinearity T
+25˚C
A
=
T
A
MAX
=
T
T
A
MIN
MIN≤TA≤TMAX
(Note 7)
Sensor Gain T
MIN≤TA≤TMAX
(Average Slope) +10.3 +10.3 mV/˚C (max)
Load Regulation (Note 8) 0≤I
Line Regulation +4.0V≤+V
≤ +1 mA
L
≤+10V
S
(Note 8)
Quiescent Current +4.0V≤+V
(Note 9) +4.0V≤+V
Change of Quiescent 4.0V≤+V
≤+10V, +25˚C 120 120 µA (max)
S
≤+10V 160 160 µA (max)
S
≤10V 2.0 2.0 µA (max)
S
Current (Note 9)
Temperature Coefficient +2.0 +2.0 µA/˚C
of Quiescent Current
Minimum Temperature In circuit of +2.5 +2.5 ˚C (min)
for Rated Accuracy
Long Term Stability (Note 10) T
Note 1: Absolute Maximum Ratings indicate limitsbeyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions.
Note 2: See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in a current National Semiconductor Linear Data Book for other methods of soldering surface mount devices.
Note 3: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin.
Note 4: Thermal resistance of the SOT-23 package is 260˚C/W, junction to ambient when attached to a printed circuit board with 2 oz. foil as shown in
Note 5: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 6: Accuracy is defined as the error between the output voltage and 10 mv/˚C times the device’s case temperature, at specified conditions of voltage, current,
and temperature (expressed in ˚C).
Note 7: 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 8: 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 9: Quiescent current is measured using the circuit of
Note 10: 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.
Figure 1
J
,I
=
, for 1000 hours
T
MAX
=
L
Figure 1
0
±
0.12
.
LOAD
for +V
=
+50 µA, in the circuit of
=
+5Vdc. Boldface limits apply for T
S
Figure 2
(Note 5) (Note 5)
±
2.0
±
3.0
±
3.0
±
0.8
±
3.0 ˚C (max)
±
4.0 ˚C (max)
±
4.0 ˚C (max)
±
0.8 ˚C (max)
+9.7 +9.7 mV/˚C (min)
±
±
±
35
0.80
1.2
±
0.12 ˚C
±
35 mV/mA
±
0.80 mV/V (max)
±
1.2 mV/V (max)
. These
A
=
T
J
(Limit)
(max)
Figure 3
=
.
www.national.com 2
Typical Performance Characteristics To generate these curves the LM45 was mounted to a printed
circuit board as shown in
Figure 3
.
Thermal Resistance
Junction to Air
Thermal Response
in Stirred Oil Bath
with Heat Sink
DS011754-24
DS011754-27
Thermal Time Constant
Start-Up Voltage
vs Temperature
DS011754-25
DS011754-28
Thermal Response in Still Air
with Heat Sink (
Figure 3
)
DS011754-26
Quiescent Current
vs Temperature
(In Circuit of
Figure 1
)
DS011754-29
Quiescent Current
vs Temperature
(In Circuit of
Figure 2
)
DS011754-30
Accuracy vs Temperature
(Guaranteed)
DS011754-31
Noise Voltage
DS011754-32
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