Rainbow Electronics LM20 - Manual

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 operating
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 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 LM20’s quiescent current is less than 10 µA. Therefore,
self-heating is less than 0.02˚C in still air. Shutdown capa-
bility 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.
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 −55˚C to +130˚C range
n Available in an SC70 and a micro SMD package
n Predictable curvature error
n Suitable for remote applications
Key Specifications
j Accuracy at +30˚C ± 1.5 to ± 4 ˚C (max)
j Accuracy at +130˚C & −55˚C ± 2.5 to ± 5 ˚C (max)
j Power Supply Voltage Range +2.4V to +5.5V
j Current Drain 10 µA (max)
j Nonlinearity ± 0.4 % (typ)
j Output Impedance 160 Ω (max)
j Load Regulation
0 µA < I
L
< +16 µA −2.5 mV (max)
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
10090802
V
O
= (−3.88x10 −6 xT 2 ) + (−1.15x10 −2 xT) + 1.8639
where:
T is temperature, and V O is the measured output voltage of the LM20.
10090824
March 2004
LM20
2.4V
,
10µA,
SC70,
micro
SMD
T
emperature
Sensor
© 2004 National Semiconductor Corporation DS100908 www.national.com