LM45B [NSC]
SOT-23 Precision Centigrade Temperature Sensors; SOT- 23精密摄氏温度传感器
| 型号： | LM45B |
| 厂家： | 
National Semiconductor |
| 描述： | SOT-23 Precision Centigrade Temperature Sensors |
| 文件： | 总8页 (文件大小：196K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
May 1995
LM45B/LM45C
SOT-23 Precision Centigrade Temperature Sensors
Y
Portable Medical Instruments
General Description
The LM45 series are precision integrated-circuit tempera-
ture sensors, whose output voltage is linearly proportional to
the Celsius (Centigrade) temperature. The LM45 does not
require any external calibration or trimming to provide accu-
Y
HVAC
Y
Power Supply Modules
Y
Disk Drives
Y
Computers
Y
Automotive
g
a
g
racies of 2 C at room temperature and 3 C over a full
§
20 to 100 C temperature range. Low cost is assured by
§
b
§
trimming and calibration at the wafer level. The LM45’s low
output impedance, linear output, and precise inherent cali-
bration make interfacing to readout or control circuitry espe-
cially easy. It can be used with a single power supply, or with
plus and minus supplies. As it draws only 120 mA from its
Features
Y
Calibrated directly in Celsius (Centigrade)
§
10.0 mV/ C scale factor
Y
a
3 C accuracy guaranteed
Linear
§
Y
Y
Y
Y
Y
Y
Y
Y
Y
g
Rated for full 20 to 100 C range
§
b
a
§
§
supply, it has very low self-heating, less than 0.2 C in still
a
§
air. The LM45 is rated to operate over a 20 to 100 C
temperature range.
Suitable for remote applications
Low cost due to wafer-level trimming
Operates from 4.0V to 10V
b
§
§
Less than 120 mA current drain
Applications
Y
Low self-heating, 0.20 C in still air
§
Battery Management
g
Nonlinearity only 0.8 C max over temp
§
Y
FAX Machines
Low impedance output, 20X for 1 mA load
Y
Printers
Connection Diagram
SOT-23
SOT-23
Order
Device
Number
Marking
Supplied As
LM45BIM3
LM45BIM3X
LM45CIM3
LM45CIM3X
T4B
T4B
T4C
T4C
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
TL/H/11754–1
Top View
See NS Package Number M03B
(JEDEC Registration TO-236AB)
Typical Applications
TL/H/11754–3
TL/H/11754–4
e
b
V
S
Choose R
/50 mA
FIGURE 1. Basic Centigrade Temperature
1
a
a
Sensor ( 2.5 C to 100 C)
e
e
e
e
c
Temp C)
V
(10 mV/ C
§
§
§
1,000 mV at 100 C
§
OUT
OUT
a
a
a
V
§
a
250 mV at 25 C
§
b
b
200 mV at 20 C
§
FIGURE 2. Full-Range Centigrade
b
a
Temperature Sensor ( 20 C to 100 C)
§
§
C
1995 National Semiconductor Corporation
TL/H/11754
RRD-B30M75/Printed in U. S. A.
Absolute Maximum Ratings (Note 1)
a
b
b
Supply Voltage
12V to 0.2V
ESD Susceptibility (Note 3):
Human Body Model
Machine Model
a
a
2000V
TBD
Output Voltage
V
S
0.6V to 1.0V
10 mA
Output Current
b
a
65 C to 150 C
Storage Temperature
Lead Temperature
SOT Package (Note 2):
Vapor Phase (60 seconds)
Infrared (15 seconds)
§
§
Operating Ratings (Note 1)
Specified Temperature Range
(Note 4)
T
to T
MAX
215 C
§
MIN
b
b
a
20 C to 100 C
LM45B, LM45C
220 C
§
§
§
Operating Temperature Range
LM45B, LM45C
a
40 C to 125 C
§
§
4.0V to 10V
a
Supply Voltage Range ( V )
a
a
S
a
e a
in the circuit of Figure 1 for
e
e
V
S
Electrical Characteristics Unless otherwise noted, these specifications apply for
V
S
5Vdc and I
LOAD
a
a
a
a
50 mA, in the circuit of Figure 2. These specifications also apply from 2.5 C to T
§
; all other limits T
MAX
e
e
e
e a
T 25 C, unless otherwise noted.
J
5Vdc. Boldface limits apply for T
T
T
to T
§
A
J
MIN
MAX
A
LM45B
LM45C
Units
Parameter
Conditions
Typical
Limit
(Note 5)
Typical
Limit
(Limit)
(Note 5)
ea
g
g
g
g
g
g
Accuracy
(Note 6)
T
A
T
A
T
A
25 C
2.0
3.0
3.0
3.0
4.0
4.0
C (max)
C (max)
C (max)
§
MAX
MIN
§
§
§
e
e
T
T
s
s
s
s
g
g
Nonlinearity
(Note 7)
T
T
T
T
0.8
0.8
C (max)
§
MIN
A
MAX
s
a
a
a
10.3
Sensor Gain
T
MIN
T
A
9.7
10.3
9.7
mV/ C (min)
§
MAX
a
(Average Slope)
mV/ C (max)
§
mV/mA (max)
s
a
g
g
35
Load Regulation (Note 8)
0
I
1 mA
35
L
s
s
a
a
a
g
g
g
0.80
g
1.2
Line Regulation
(Note 8)
4.0V
V
S
10V
0.80
mV/V (max)
mV/V (max)
1.2
s
s
s
s
a
a
a
a
a
a
a
10V, 25 C
10V
Quiescent Current
(Note 9)
4.0V
4.0V
V
V
120
120
mA (max)
mA (max)
§
S
160
160
S
s
s
10V
a
Change of Quiescent
Current (Note 8)
4.0V
V
S
2.0
2.0
mA (max)
Temperature Coefficient
of Quiescent Current
a
a
2.0
2.0
mA/ C
§
Minimum Temperature
for Rated Accuracy
In circuit of
a
a
2.5
2.5
C (min)
§
e
Figure 1, I
0
L
e
g
g
0.12
Long Term Stability (Note 10)
T
T
, for 1000 hours
0.12
C
§
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
J
MAX
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 kX 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 Figure 3.
§
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
computed by multiplying the internal dissipation by the thermal resistance.
Note 9: Quiescent current is measured using the circuit of Figure 1.
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.
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 Still Air
with Heat Sink (Figure 3)
Thermal Time Constant
54–23
sed
for Heat Sink to Generate All Curves.
TL/H/11754–5
(/2 Square Printed Circuit Board
×
with 2 oz. Foil or Similar
3
Applications
The LM45 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or
cemented to a surface and its temperature will be within
about 0.2 C of the surface temperature.
§
This presumes that the ambient air temperature is almost
the same as the surface temperature; if the air temperature
were much higher or lower than the surface temperature,
the actual temperature of the LM45 die would be at an inter-
mediate temperature between the surface temperature and
the air temperature.
into a threaded hole in a tank. As with any IC, the LM45 and
accompanying wiring and circuits must be kept insulated
and dry, to avoid leakage and corrosion. This is especially
true if the circuit may operate at cold temperatures where
condensation can occur. Printed-circuit coatings and var-
nishes such as Humiseal and epoxy paints or dips are often
used to insure that moisture cannot corrode the LM45 or its
connections.
Temperature Rise of LM45 Due to Self-Heating
(Thermal Resistance)
To ensure good thermal conductivity the backside of the
LM45 die is directly attached to the GND pin. The lands and
traces to the LM45 will, of course, be part of the printed
circuit board, which is the object whose temperature is be-
ing measured. These printed circuit board lands and traces
will not cause the LM45s temperature to deviate from the
desired temperature.
SOT-23**
no heat sink
SOT-23
small heat fin*
Still air
Moving air
450 C/W
260 C/W
§
§
180 C/W
§
* Heat sink used is (/2 square printed circuit board with 2 oz. foil with part
×
attached as shown in Figure 3.
** Part soldered to 30 gauge wire.
Alternatively, the LM45 can be mounted inside a sealed-end
metal tube, and can then be dipped into a bath or screwed
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; seeFigure 4. Or you can improve the tolerance of
capacitance with a series R-C damper from output to
ground; see Figure 5.
TL/H/11754–9
Any linear circuit connected to wires in a hostile environ-
ment can have its performance affected adversely by in-
tense electromagnetic sources such as relays, radio trans-
mitters, motors 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 cas-
FIGURE 5. LM45 with R-C Damper
es, a bypass capacitor from V to ground and a series R-C
IN
damper such as 75X in series with 0.2 or 1 mF from output
to ground, as shown in Figure 5, are often useful.
TL/H/11754–12
TL/H/11754–8
FIGURE 6. Temperature Sensor,
FIGURE 4. LM45 with Decoupling from Capacitive Load
b
a
Single Supply, 20 C to 100 C
§
§
4
Typical Applications (Continued)
TL/H/11754–14
a
FIGURE 7. 4-to-20 mA Current Source (0 C to 100 C)
§
§
TL/H/11754–15
FIGURE 8. Fahrenheit Thermometer
TL/H/11754–16
FIGURE 9. Centigrade Thermometer (Analog Meter)
TL/H/11754–17
FIGURE 10. Expanded Scale Thermometer
(50 to 80 Fahrenheit, for Example Shown)
§
§
TL/H/11754–18
a
FIGURE 11. Temperature To Digital Converter (Serial Output) ( 128 C Full Scale)
§
5
Typical Applications (Continued)
TL/H/11754–19
FIGURE 12. Temperature To Digital Converter (Parallel TRI-STATE Outputs for
É
Standard Data Bus to mP Interface) (128 C Full Scale)
§
TL/H/11754–20
e
-Trim R for V
*
1% or 2% film resistor
e
e
e
3.075V
1.955V
0.075V
B
B
C
A
-Trim R for V
C
-Trim R for V
A
a
c
T
100mV/ C
§
ambient
e
-Example, V
2.275V at 22 C
§
A
FIGURE 13. Bar-Graph Temperature Display (Dot Mode)
6
Typical Applications (Continued)
TL/H/11754–21
FIGURE 14. LM45 With Voltage-To-Frequency Converter And Isolated Output
a
(2.5 C to 100 C; 25 Hz to 1000 Hz)
§
§
Block Diagram
TL/H/11754–22
7
Physical Dimensions inches (millimeters)
SOT-23 Molded Small Outline Transistor Package (M3)
Order Number LM45BIM3, LM45BIM3X, LM45CIM3 or LM45CIM3X
NS Package Number M03B
(JEDEC Registration TO-236AB)
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and whose
failure to perform, when properly used in accordance
with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury
to the user.
2. A critical component is any component of a life
support device or system whose failure to perform can
be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or
effectiveness.
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