LM19
2.4V, 10A, TO-92 Temperature Sensor
General Description
The LM19 is a precision analog output CMOS integrated-
circuit temperature sensor that operates over a -55C to
+130C temperature range. The power supply operating
range is +2.4 V to +5.5 V. The transfer function of LM19 is
predominately linear, yet has a slight predictable parabolic
curvature. The accuracy of the LM19 when specified to a
parabolic transfer function is
2.5C at an ambient tempera-
ture of +30C. The temperature error increases linearly and
reaches a maximum of
3.8C at the temperature range
extremes. The temperature range is affected by the power
supply voltage. At a power supply voltage of 2.7 V to 5.5 V
the temperature range extremes are +130C and -55C.
Decreasing the power supply voltage to 2.4 V changes the
negative extreme to -30C, while the positive remains at
+130C.
The LM19's quiescent current is less than 10 A. Therefore,
self-heating is less than 0.02C in still air. Shutdown capa-
bility for the LM19 is intrinsic because its inherent low power
consumption allows it to be powered directly from the output
of many logic gates or does not necessitate shutdown at all.
Applications
n
Cellular Phones
n
Computers
n
Power Supply Modules
n
Battery Management
n
FAX Machines
n
Printers
n
HVAC
n
Disk Drives
n
Appliances
Features
n
Rated for full -55C to +130C range
n
Available in a TO-92 package
n
Predictable curvature error
n
Suitable for remote applications
Key Specifications
j
Accuracy at +30C
2.5 C (max)
j
Accuracy at +130C & -55C
3.5 to
3.8 C (max)
j
Power Supply Voltage Range
+2.4V to +5.5V
j
Current Drain
10 A (max)
j
Nonlinearity
0.4 % (typ)
j
Output Impedance
160
(max)
j
Load Regulation
0 A
<
I
L
<
+16 A
-2.5 mV (max)
Typical Application
Output Voltage vs Temperature
20004002
V
O
= (-3.88x10
-6
xT
2
) + (-1.15x10
-2
xT) + 1.8639
or
where:
T is temperature, and V
O
is the measured output voltage of the LM19.
20004024
FIGURE 1. Full-Range Celsius (Centigrade) Temperature Sensor (-55C to +130C)
Operating from a Single Li-Ion Battery Cell
January 2003
LM19
2.4V
,
10A,
T
O-92
T
emperature
Sensor
2003 National Semiconductor Corporation
DS200040
www.national.com
Typical Application
(Continued)
Temperature (T)
Typical V
O
+130C
+303 mV
+100C
+675 mV
+80C
+919 mV
+30C
+1515 mV
+25C
+1574 mV
0C
+1863.9 mV
-30C
+2205 mV
-40C
+2318 mV
-55C
+2485 mV
Connection Diagram
TO-92
20004001
See NS Package Number Z03A
Ordering Information
Order
Temperature
Temperature
NS Package
Device
Number
Accuracy
Range
Number
Marking
Transport Media
LM19CIZ
3.8C
-55C to +130C
Z03A
LM19CIZ
Bulk
LM19
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2
Absolute Maximum Ratings
(Note 1)
Supply Voltage
+6.5V to -0.2V
Output Voltage
(V
+
+ 0.6 V) to
-0.6 V
Output Current
10 mA
Input Current at any pin (Note 2)
5 mA
Storage Temperature
-65C to
+150C
Maximum Junction Temperature
(T
JMAX
)
+150C
ESD Susceptibility (Note 3) :
Human Body Model
2500 V
Machine Model
250 V
Lead Temperature
TO-92 Package
Soldering (3 seconds dwell)
+240C
Operating Ratings
(Note 1)
Specified Temperature Range:
T
MIN
T
A
T
MAX
2.4 V
V
+
2.7 V
-30C
T
A
+130C
2.7 V
V
+
5.5 V
-55C
T
A
+130C
Supply Voltage Range (V
+
)
+2.4 V to +5.5 V
Thermal Resistance,
JA
(Note 4)
TO-92
150C/W
Electrical Characteristics
Unless otherwise noted, these specifications apply for V
+
= +2.7 V
DC
. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all
other limits T
A
= T
J
= 25C; Unless otherwise noted.
Parameter
Conditions
Typical
(Note 5)
LM19C
Units
(Limit)
Limits
(Note 6)
Temperature to Voltage Error
V
O
= (-3.88x10
-6
xT
2
)
+ (-1.15x10
-2
xT) + 1.8639V
(Note 7)
T
A
= +25C to +30C
2.5
C (max)
T
A
= +130C
3.5
C (max)
T
A
= +125C
3.5
C (max)
T
A
= +100C
3.2
C (max)
T
A
= +85C
3.1
C (max)
T
A
= +80C
3.0
C (max)
T
A
= 0C
2.9
C (max)
T
A
= -30C
3.3
C (min)
T
A
= -40C
3.5
C (max)
T
A
= -55C
3.8
C (max)
Output Voltage at 0C
+1.8639
V
Variance from Curve
1.0
C
Non-Linearity (Note 8)
-20C
T
A
+80C
0.4
%
Sensor Gain (Temperature
Sensitivity or Average Slope)
to equation:
V
O
=-11.77 mV/CxT+1.860V
-30C
T
A
+100C
-11.77
-11.0
-12.6
mV/C (min)
mV/C (max)
Output Impedance
0 A
I
L
+16 A
(Notes 10, 11)
160
(max)
Load Regulation(Note 9)
0 A
I
L
+16 A
(Notes 10, 11)
-2.5
mV (max)
Line Regulation
+2. 4 V
V
+
+5.0V
+3.7
mV/V (max)
+5.0 V
V
+
+5.5 V
+11
mV (max)
Quiescent Current
+2. 4 V
V
+
+5.0V
4.5
7
A (max)
+5.0V
V
+
+5.5V
4.5
9
A (max)
+2. 4 V
V
+
+5.0V
4.5
10
A (max)
Change of Quiescent Current
+2. 4 V
V
+
+5.5V
+0.7
A
Temperature Coefficient of
-11
nA/C
Quiescent Current
Shutdown Current
V
+
+0.8 V
0.02
A
LM19
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3
Electrical Characteristics
(Continued)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: When the input voltage (V
I
) at any pin exceeds power supplies (V
I
<
GND or V
I
>
V
+
), the current at that pin should be limited to 5 mA.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 k
resistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
Note 4: The junction to ambient thermal resistance (
JA
) is specified without a heat sink in still air.
Note 5: Typicals are at T
J
= T
A
= 25C and represent most likely parametric norm.
Note 6: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 7: Accuracy is defined as the error between the measured and calculated output voltage at the specified conditions of voltage, current, and temperature
(expressed inC).
Note 8: Non-Linearity is defined as the deviation of the calculated output-voltage-versus-temperature curve from the best-fit straight line, over the temperature
range specified.
Note 9: 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 10: Negative currents are flowing into the LM19. Positive currents are flowing out of the LM19. Using this convention the LM19 can at most sink -1 A and
source +16 A.
Note 11: Load regulation or output impedance specifications apply over the supply voltage range of +2.4V to +5.5V.
Note 12: Line regulation is calculated by subtracting the output voltage at the highest supply input voltage from the output voltage at the lowest supply input voltage.
Typical Performance Characteristics
Temperature Error vs. Temperature
Thermal Response in Still Air
20004034
20004035
1.0 LM19 Transfer Function
The LM19's transfer function can be described in different
ways with varying levels of precision. A simple linear transfer
function, with good accuracy near 25C, is
V
O
= -11.69 mV/C x T + 1.8663 V
Over the full operating temperature range of -55C to
+130C, best accuracy can be obtained by using the para-
bolic transfer function
V
O
= (-3.88x10
-6
xT
2
) + (-1.15x10
-2
xT) + 1.8639
solving for T:
A linear transfer function can be used over a limited tempera-
ture range by calculating a slope and offset that give best
results over that range. A linear transfer function can be
calculated from the parabolic transfer function of the LM19.
The slope of the linear transfer function can be calculated
using the following equation:
m = -7.76 x 10
-6
x T - 0.0115,
where T is the middle of the temperature range of interest
and m is in V/C. For example for the temperature range of
T
min
=-30 to T
max
=+100C:
T=35C
and
m = -11.77 mV/C
The offset of the linear transfer function can be calculated
using the following equation:
b = (V
OP
(T
max
) + V
OP
(T) + m x (T
max
+T))/2
,
where:
V
OP
(T
max
) is the calculated output voltage at T
max
using
the parabolic transfer function for V
O
V
OP
(T) is the calculated output voltage at T using the
parabolic transfer function for V
O
.
Using this procedure the best fit linear transfer function for
many popular temperature ranges was calculated in Figure
2. As shown in Figure 2 the error that is introduced by the
linear transfer function increases with wider temperature
ranges.
LM19
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4
1.0 LM19 Transfer Function
(Continued)
2.0 Mounting
The LM19 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or
cemented to a surface. The temperature that the LM19 is
sensing will be within about +0.02C of the surface tempera-
ture to which the LM19's leads are attached.
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 measured would be at an intermediate
temperature between the surface temperature and the air
temperature.
To ensure good thermal conductivity the backside of the
LM19 die is directly attached to the GND pin. The temper-
tures of the lands and traces to the other leads of the LM19
will also affect the temperature that is being sensed.
Alternatively, the LM19 can be mounted inside a sealed-end
metal tube, and can then be dipped into a bath or screwed
into a threaded hole in a tank. As with any IC, the LM19 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 conden-
sation can occur. Printed-circuit coatings and varnishes such
as Humiseal and epoxy paints or dips are often used to
ensure that moisture cannot corrode the LM19 or its connec-
tions.
The thermal resistance junction to ambient (
JA
) is the pa-
rameter used to calculate the rise of a device junction tem-
perature due to its power dissipation. For the LM19 the
equation used to calculate the rise in the die temperature is
as follows:
T
J
= T
A
+
JA
[(V
+
I
Q
) + (V
+
- V
O
) I
L
]
where I
Q
is the quiescent current and I
L
is the load current on
the output. Since the LM19's junction temperature is the
actual temperature being measured care should be taken to
minimize the load current that the LM19 is required to drive.
The tables shown in Figure 3 summarize the rise in die
temperature of the LM19 without any loading, and the ther-
mal resistance for different conditions.
3.0 Capacitive Loads
The LM19 handles capacitive loading well. Without any pre-
cautions, the LM19 can drive any capacitive load less than
300 pF as shown in Figure 4. Over the specified temperature
range the LM19 has a maximum output impedance of 160
.
In an extremely noisy environment it may be necessary to
add some filtering to minimize noise pickup. It is recom-
mended that 0.1 F be added from V
+
to GND to bypass the
power supply voltage, as shown in Figure 5. In a noisy
environment it may even be necessary to add a capacitor
from the output to ground with a series resistor as shown in
Figure 5. A 1 F output capacitor with the 160
maximum
output impedance and a 200
series resistor will form a 442
Hz lowpass filter. Since the thermal time constant of the
LM19 is much slower, the overall response time of the LM19
will not be significantly affected.
Temperature Range
Linear Equation
V
O
=
Maximum Deviation of Linear Equation
from Parabolic Equation (C)
T
min
(C)
T
max
(C)
-55
+130
-11.79 mV/C x T + 1.8528 V
1.41
-40
+110
-11.77 mV/C x T + 1.8577 V
0.93
-30
+100
-11.77 mV/C x T + 1.8605 V
0.70
-40
+85
-11.67 mV/C x T + 1.8583 V
0.65
-10
+65
-11.71 mV/C x T + 1.8641 V
0.23
+35
+45
-11.81 mV/C x T + 1.8701 V
0.004
+20
+30
-11.69 mV/C x T + 1.8663 V
0.004
FIGURE 2. First Order Equations Optimized For Different Temperature Ranges.
TO-92
TO-92
no heat sink
small heat fin
JA
T
J
- T
A
JA
T
J
- T
A
(C/W)
(C)
(C/W)
(C)
Still air
150
TBD
TBD
TBD
Moving air
TBD
TBD
TBD
TBD
FIGURE 3. Temperature Rise of LM19 Due to
Self-Heating and Thermal Resistance (
JA
)
20004015
FIGURE 4. LM19 No Decoupling Required for
Capacitive Loads Less than 300 pF.
LM19
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5
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