LM20 2.4V, 10µA, SC70, micro SMD Temperature Sensor
October 1999
LM20
2.4V, 10µA, SC70, micro SMD Temperature Sensor
General Description
The LM20 is a precision analog output CMOS
integrated-circuit temperature sensor that operates over a
−55˚C to +130˚C temperature range. The power supply op-
erating range is +2.4 V to +5.5 V. The transfer function of
LM20 is predominately linear, yet has a slight predictable
parabolic curvature. The accuracy of the LM20 when speci-
fied to a parabolic transfer function is
±
1.5˚C at an ambient
temperature of +30˚C. The temperature error increases lin-
early 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 LM20’s quiescent current is less than 10 µA. Therefore,
self-heating is less than 0.02˚C in still air. Shutdown capabil-
ity for the LM20 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.
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Battery Management
FAX Machines
Printers
HVAC
Disk Drives
Appliances
Features
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Rated for full −55˚C to +130˚C range
Available in an SC70 and a micro SMD package
Predictable curvature error
Suitable for remote applications
Key Specifications
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Accuracy at +30˚C
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Accuracy at +130˚C & −55˚C
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Power Supply Voltage Range
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Current Drain
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Nonlinearity
n
Output Impedance
n
Load Regulation
0 µA
<
I
L
<
+16 µA
±
1.5 to
±
4 ˚C (max)
±
2.5 to
±
5 ˚C (max)
+2.4V to +5.5V
10 µA (max)
±
0.4 % (typ)
160
Ω
(max)
−2.5 mV (max)
Applications
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Cellular Phones
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Computers
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Power Supply Modules
Typical Application
Output Voltage vs Temperature
DS100908-2
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 LM20.
DS100908-24
Full-Range Celsius (Centigrade) Temperature Sensor (−55˚C to +130˚C)
Operating from a Single Li-Ion Battery Cell
© 1999 National Semiconductor Corporation
DS100908
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
