LM20EP
Enhanced Plastic 2.4V, 10µA, SC70, micro SMD
Temperature Sensor
General Description
The LM20EP is a precision analog output CMOS integrated-
circuit temperature sensor that operates over a −55˚C to
+130˚C temperature range. The power supply operating
range is +2.4 V to +5.5 V. The transfer function of LM20EP is
predominately linear, yet has a slight predictable parabolic
curvature. The accuracy of the LM20EP when specified to a
parabolic transfer function is ±1.5˚C at an ambient tempera-
ture of +30˚C. The temperature error increases linearly and
reaches a maximum of ±2.5˚C 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 +130˚C and −55˚C.
Decreasing the power supply voltage to 2.4 V changes the
negative extreme to −30˚C, while the positive remains at
+130˚C.
The LM20EP’s quiescent current is less than 10 µA. There-
fore, self-heating is less than 0.02˚C in still air. Shutdown
capability for the LM20EP 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.
ENHANCED PLASTIC
•Extended Temperature Performance of −55˚C to +130˚C
•Baseline Control - Single Fab & Assembly Site
•Process Change Notification (PCN)
•Qualification & Reliability Data
•Solder (PbSn) Lead Finish is standard
•Enhanced Diminishing Manufacturing Sources (DMS)
Support
Features
nRated for full −55˚C to +130˚C range
nAvailable in an SC70 and a micro SMD package
nPredictable curvature error
nSuitable for remote applications
Key Specifications
jAccuracy at +30˚C ±1.5 to ±4 ˚C (max)
jAccuracy at +130˚C & −55˚C ±2.5 to ±5 ˚C (max)
jPower Supply Voltage Range +2.4V to +5.5V
jCurrent Drain 10 µA (max)
jNonlinearity ±0.4 % (typ)
jOutput Impedance 160 Ω(max)
jLoad Regulation
0µA<I
L
<+16 µA −2.5 mV (max)
Applications
nBattery Management
nSelected Military Applications
nSelected Avionics Applications
Ordering Information
PART NUMBER VID PART NUMBER NS PACKAGE NUMBER (Note 3)
LM20CIM7EP V62/04728-01 MAA05A
(Notes 1, 2) TBD TBD
Note 1: For the following (Enhanced Plastic) version, check for availability: LM20SIBPEP, LM20SIBPXEP, LM20BIM7EP, LM20BIM7XEP,
LM20CIM7XEP, LM20SITLEP, LM20SITLXEP. Parts listed with an "X" are provided in Tape & Reel and parts without an "X" are in Rails.
Note 2: FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/
mil
Note 3: Refer to package details under Physical Dimensions
May 2004
LM20EP Enhanced Plastic 2.4V, 10µA, SC70, micro SMD Temperature Sensor
© 2004 National Semiconductor Corporation DS200999 www.national.com
Typical Application
Full-Range Celsius (Centigrade) Temperature Sensor (−55˚C to +130˚C)
Operating from a Single Li-Ion Battery Cell
Output Voltage vs Temperature
20099902
V
O
= (−3.88x10
−6
xT
2
) + (−1.15x10
−2
xT) + 1.8639
where:
T is temperature, and VOis the measured output voltage of the LM20EP.
20099924
Temperature (T) Typical V
O
+130˚C +303 mV
+100˚C +675 mV
+80˚C +919 mV
+30˚C +1515 mV
+25˚C +1574 mV
0˚C +1863.9 mV
−30˚C +2205 mV
−40˚C +2318 mV
−55˚C +2485 mV
Connection Diagrams
SC70-5 micro SMD
20099901
Note:
- GND (pin 2) may be grounded or left floating. For optimum thermal
conductivity to the pc board ground plane pin 2 should be grounded.
- NC (pin 1) should be left floating or grounded. Other signal traces
should not be connected to this pin.
Top View
See NS Package Number MAA05A
20099932
Note:
- Pin numbers are referenced to the package marking text orientation.
- Reference JEDEC Registration MO-211, variation BA
- The actual physical placement of package marking will vary slightly from
part to part. The package marking will designate the date code and will vary
considerably. Package marking does not correlate to device type in any way.
Top View
See NS Package Number BPA04DDC and TLA04ZZA
LM20EP Enhanced Plastic
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Absolute Maximum Ratings (Note 4)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
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 5) 5 mA
Storage Temperature −65˚C to
+150˚C
Maximum Junction Temperature
(T
JMAX
) +150˚C
ESD Susceptibility (Note 6) :
Human Body Model 2500 V
Machine Model 250 V
Lead Temperature
SC-70 Package (Note 7) :
Vapor Phase (60 seconds) +215˚C
Infrared (15 seconds) +220˚C
Operating Ratings(Note 4)
Specified Temperature Range: T
MIN
≤T
A
≤T
MAX
LM20BEP, LM20CEP with
2.4 V ≤V
+
≤2.7 V −30˚C ≤T
A
≤+130˚C
LM20BEP, LM20CEP with
2.7 V ≤V
+
≤5.5 V −55˚C ≤T
A
≤+130˚C
LM20SEP with
2.4 V ≤V
+
≤5.5 V −30˚C ≤T
A
≤+125˚C
LM20SEP with
2.7 V ≤V
+
≤5.5 V −40˚C ≤T
A
≤+125˚C
Supply Voltage Range (V
+
) +2.4 V to +5.5 V
Thermal Resistance, θ
JA
(Note 8)
SC-70
micro SMD
415˚C/W
340˚C/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
= 25˚C; Unless otherwise noted.
Parameter Conditions Typical
(Note 9)
LM20BEP LM20CEP LM20SEP Units
(Limit)
Limits Limits Limits
(Note 10) (Note 10) (Note 10)
Temperature to Voltage Error
V
O
= (−3.88x10
−6
xT
2
)
+ (−1.15x10
−2
xT) + 1.8639V
(Note 11)
T
A
= +25˚C to +30˚C ±1.5 ±4.0 ±2.5 ˚C (max)
T
A
= +130˚C ±2.5 ±5.0 ˚C (max)
T
A
= +125˚C ±2.5 ±5.0 ±3.5 ˚C (max)
T
A
= +100˚C ±2.2 ±4.7 ±3.2 ˚C (max)
T
A
= +85˚C ±2.1 ±4.6 ±3.1 ˚C (max)
T
A
= +80˚C ±2.0 ±4.5 ±3.0 ˚C (max)
T
A
= 0˚C ±1.9 ±4.4 ±2.9 ˚C (max)
T
A
= −30˚C ±2.2 ±4.7 ±3.3 ˚C (min)
T
A
= −40˚C ±2.3 ±4.8 ±3.5 ˚C (max)
T
A
= −55˚C ±2.5 ±5.0 ˚C (max)
Output Voltage at 0˚C +1.8639 V
Variance from Curve ±1.0 ˚C
Non-Linearity (Note 12) −20˚C ≤T
A
≤+80˚C ±0.4 %
Sensor Gain (Temperature
Sensitivity or Average Slope)
to equation:
V
O
=−11.77 mV/˚CxT+1.860V
−30˚C ≤T
A
≤+100˚C −11.77 −11.4
−12.2
−11.0
−12.6
−11.0
−12.6
mV/˚C (min)
mV/˚C (max)
Output Impedance 0 µA ≤I
L
≤+16 µA
(Notes 14, 15)
160 160 160 Ω(max)
Load Regulation(Note 13) 0 µA ≤I
L
≤+16 µA
(Notes 14, 15)
−2.5 −2.5 −2.5 mV (max)
Line Regulation +2. 4 V ≤V
+
≤+5.0V +3.3 +3.7 +3.7 mV/V (max)
+5.0 V ≤V
+
≤+5.5 V +11 +11 +11 mV (max)
Quiescent Current +2. 4V ≤V
+
≤+5.0V 4.5 7 7 7 µA (max)
+5.0V ≤V
+
≤+5.5V 4.5 9 9 9 µA (max)
+2. 4V ≤V
+
≤+5.0V 4.5 10 10 10 µA (max)
Change of Quiescent Current +2. 4 V ≤V
+
≤+5.5V +0.7 µA
Temperature Coefficient of −11 nA/˚C
LM20EP Enhanced Plastic
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Electrical Characteristics (Continued)
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
= 25˚C; Unless otherwise noted.
Parameter Conditions Typical
(Note 9)
LM20BEP LM20CEP LM20SEP Units
(Limit)
Limits Limits Limits
(Note 10) (Note 10) (Note 10)
Quiescent Current
Shutdown Current V
+
≤+0.8 V 0.02 µA
Note 4: 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 5: When the input voltage (VI) at any pin exceeds power supplies (VI<GND or VI>V+), the current at that pin should be limited to 5 mA.
Note 6: The human body model is a 100 pF capacitor discharged through a 1.5 kΩresistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
Note 7: See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in any post 1986 National
Semiconductor Linear Data Book for other methods of soldering surface mount devices.
Note 8: The junction to ambient thermal resistance (θJA) is specified without a heat sink in still air using the printed circuit board layout shown in Figure 1.
Note 9: Typicals are at TJ=T
A= 25˚C and represent most likely parametric norm.
Note 10: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 11: Accuracy is defined as the error between the measured and calculated output voltage at the specified conditions of voltage, current, and temperature
(expressed in˚C).
Note 12: 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 13: 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 14: Negative currents are flowing into the LM20EP. Positive currents are flowing out of the LM20EP. Using this convention the LM20EP can at most sink −1
µA and source +16 µA.
Note 15: Load regulation or output impedance specifications apply over the supply voltage range of +2.4V to +5.5V.
Note 16: 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 Characteristic
Temperature Error vs Temperature
20099925
PCB Layouts Used for Thermal Measurements
20099929
a) Layout used for no heat sink measurements.
20099930
b) Layout used for measurements with small heat hink.
FIGURE 1. PCB Lyouts used for thermal measurements.
LM20EP Enhanced Plastic
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LM20EP Transfer Function
The LM20EP’s transfer function can be described in different
ways with varying levels of precision. A simple linear transfer
function, with good accuracy near 25˚C, is
V
O
= −11.69 mV/˚C x T + 1.8663 V
Over the full operating temperature range of −55˚C to
+130˚C, 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
LM20EP. 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
=+100˚C:
T=35˚C
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)+mx(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.
Mounting
The LM20EP 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 LM20EP is
sensing will be within about +0.02˚C of the surface tempera-
ture to which the LM20EP’s leads are attached to.
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
LM20EP die is directly attached to the pin 2 GND pin. The
tempertures of the lands and traces to the other leads of the
LM20EP will also affect the temperature that is being
sensed.
Alternatively, the LM20EP 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
LM20EP 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
varnishes such as Humiseal and epoxy paints or dips are
often used to ensure that moisture cannot corrode the
LM20EP or its connections.
The thermal resistance junction to ambient (θ
JA
) is the pa-
rameter used to calculate the rise of a device junction tem-
perature due to its power dissipation. For the LM20EP the
equation used to calculate the rise in the die temperature is
as follows:
T
J
=T
A
+θ
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 LM20EP’s junction temperature is the
actual temperature being measured care should be taken to
minimize the load current that the LM20EP is required to
drive.
The tables shown in Figure 3 summarize the rise in die
temperature of the LM20EP without any loading, and the
thermal resistance for different conditions.
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.
LM20EP Enhanced Plastic
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Mounting (Continued)
Capacitive Loads
The LM20EP handles capacitive loading well. Without any
precautions, the LM20EP can drive any capacitive load less
than 300 pF as shown in Figure 4. Over the specified tem-
perature range the LM20EP has a maximum output imped-
ance of 160 Ω. In an extremely noisy environment it may be
necessary to add some filtering to minimize noise pickup. It
is recommended that 0.1 µF be added from V
+
to GND to
bypass the power supply voltage, as shown in Figure 5.Ina
noisy environment it may even be necessary to add a ca-
pacitor from the output to ground with a series resistor as
shown in Figure 5. A 1 µF output capacitor with the 160 Ω
maximum output impedance and a 200 Ωseries resistor will
form a 442 Hz lowpass filter. Since the thermal time constant
of the LM20EP is much slower, the overall response time of
the LM20EP will not be significantly affected.
SC70-5 SC70-5
no heat sink small heat sink
θ
JA
T
J
−T
A
θ
JA
T
J
−T
A
(˚C/W) (˚C) (˚C/W) (˚C)
Still air 412 0.2 350 0.19
SC70-5 SC70-5
no heat sink small heat sink
θ
JA
T
J
−T
A
θ
JA
T
J
−T
A
(˚C/W) (˚C) (˚C/W) (˚C)
Moving air 312 0.17 266 0.15
See Figure 1 for PCB layout samples.
micro SMD micro SMD
no heat sink small heat fin
θ
JA
T
J
−T
A
θ
JA
T
J
−T
A
(˚C/W) (˚C) (˚C/W) (˚C)
Still air 340 0.18 TBD TBD
micro SMD micro SMD
no heat sink small heat fin
θ
JA
T
J
−T
A
θ
JA
T
J
−T
A
(˚C/W) (˚C) (˚C/W) (˚C)
Moving air TBD TBD TBD TBD
FIGURE 3. Temperature Rise of LM20EP Due to
Self-Heating and Thermal Resistance (θ
JA
)
20099915
FIGURE 4. LM20EP No Decoupling Required for
Capacitive Loads Less than 300 pF.
R(Ω) C (µF)
200 1
470 0.1
680 0.01
1 k 0.001
20099916 20099933
FIGURE 5. LM20EP with Filter for Noisy Environment and Capacitive Loading greater than 300 pF. Either placement
of resistor as shown above is just as effective.
LM20EP Enhanced Plastic
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LM20EP micro SMD Light
Sensitivity
Exposing the LM20EP micro SMD package to bright sunlight
may cause the output reading of the LM20EP to drop by
1.5V. In a normal office environment of fluorescent lighting
the output voltage is minimally affected (less than a millivolt
drop). In either case it is recommended that the LM20EP
micro SMD be placed inside an enclosure of some type that
minimizes its light exposure. Most chassis provide more than
ample protection. The LM20EP does not sustain permanent
damage from light exposure. Removing the light source will
cause LM20EP’s output voltage to recover to the proper
value.
Applications Circuits
20099918
FIGURE 6. Centigrade Thermostat
20099919
FIGURE 7. Conserving Power Dissipation with Shutdown
20099928
Most CMOS ADCs found in ASICs have a sampled data comparator input structure that is notorious for causing grief to analog
output devices such as the LM20EP and many op amps. The cause of this grief is the requirement of instantaneous charge of the
input sampling capacitor in the ADC. This requirement is easily accommodated by the addition of a capacitor. Since not all ADCs
have identical input stages, the charge requirements will vary necessitating a different value of compensating capacitor. This ADC
is shown as an example only. If a digital output temperature is required please refer to devices such as the LM74.
FIGURE 8. Suggested Connection to a Sampling Analog to Digital Converter Input Stage
LM20EP Enhanced Plastic
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Physical Dimensions inches (millimeters) unless otherwise noted
5-Lead SC70 Molded Package
NS Package Number MAA05A
4-Bump micro SMD Ball Grid Array Package (Small Bump)
NS Package Number BPA04DDC
The following dimensions apply to the BPA04DDC package
shown above: X1=X2 = 853µm ±30µm, X3= 900µm ±50µm
LM20EP Enhanced Plastic
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
4-Bump micro SMD Ball Grid Array Package (Large Bump)
NS Package Number TLA04ZZA
The following dimensions apply to the TLA04ZZA package
shown above: X1=X2 = 963µm ±30µm, X3= 600µm ±75µm
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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 AND GENERAL
COUNSEL 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.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products
Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification
(CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2.
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LM20EP Enhanced Plastic 2.4V, 10µA, SC70, micro SMD Temperature Sensor
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
