The LM335 solid-state temperature sensor produces an output of 10mV
per degree Kelvin. Kelvin can be converted to Celsius by subtracting 273 or 2.73 volts
from the reading. The sensors high sensitivity allow it to be used with 10-bit
or 12-bit analog inputs directly with only the use of a 1K ohm bias resistor. The
following diagram shows the connection of an LM335 to an
which features 12-bit analog
inputs. The reading can be converted to Celsius using the following formula and
resolution is approx. 0.1 degrees Celsius;
C= ( reading-2235.9)/ 8.19
10 OPEN "COM1:9600,N,8,1,CS,DS,RS" AS#1
30 LOCATE 1,1
40 PRINT#1, "RD0"
50 INPUT#1, READING
60 CEL= ( READING/2235.9)/8.19
70 PRINT " TEMPERATURE IS " CEL, "DEGREES CELCIUS"
80 GOTO 30
analog input resolution is 10-bits and
allows a resolution of 0.5 Degrees Celcius. The following formula is used to
calculate temperature in Celsius.
C= ( reading-558.6)/ 2.048
analog input resolution is 8-bits and allows a resolution
of 2 degrees C. The following formula is used to calculate temperature in Celsius.
C= ( reading-139.2 )/0.512
( NOTE : The
LM335 sensor can be purchased from Digi-Key as part # LM335AZ-ND. Their phone number is
1-800-344-4539 and costs around $5 U.S. Digi-Key accepts all major credit cards and the
part is always in stock.)
Back to Applications Page