
LM20
2.4V, 10μA, SC70, micro SMD Temperature Sensor
General Description
The
LM20
is
integrated-circuit temperature sensor that operates over a
55C to +130C 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
±
1.5C at an ambient
temperature of +30C. The temperature error increases lin-
early and reaches a maximum of
±
2.5C 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 LM20’s quiescent current is less than 10 μA. Therefore,
self-heating is less than 0.02C 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.
a
precision
analog
output
CMOS
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 an SC70 and a micro SMD package
n
Predictable curvature error
n
Suitable for remote applications
Key Specifications
n
Accuracy at +30C
n
Accuracy at +130C & 55C
n
Power Supply Voltage Range
n
Current Drain
n
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
(max)
2.5 mV (max)
Typical Application
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.
Output Voltage vs Temperature
DS100908-24
Full-Range Celsius (Centigrade) Temperature Sensor (55C to +130C)
Operating from a Single Li-Ion Battery Cell
October 1999
L
1999 National Semiconductor Corporation
DS100908
www.national.com