ILX Lightwave Temperature Controller LDT-5525 User Manual page 53

The LDT-5525 Temperature Controller uses v to determine the nominal
temperature, T
T
n
- where T
The temperature, T
is first calibrated as follows:
T
d
- where C1 and C2 are the constants stored by the user in the LDT-5525
Temperature Controller for the LM335.
When the LDT-5525 is shipped from the factory, the LM335 measurement system
is calibrated, but the sensor (C1 and C2) is not. Nominally, C1 = 0, and C2 = 1. In
that case, the temperature accuracy is typically +1
range. With C1 and C2 calibrated also, the temperature accuracy is typically +0.3
o
C over the rated operating range. The temperature accuracy may be improved
over a narrow temperature range by a two-point calibration of C1 and C2.
However, the LM335 is not perfectly linear, and even with C1 accurately known
(and C2 uncalibrated) there is a non-linear absolute temperature error associated
with the device. This non-linearity caused error is typically +0.3
associated with C1 assumed to be zero.
If a maximum absolute error of +1
required, just set C1 = 0, C2 = 1. If a maximum absolute error of +0.5
tolerable, the one point calibration of C1 may be used (see page C-5). If a greater
accuracy is desired, the two point method of determining C1 and C2 should used
(see page C-6). Note however, the absolute error associated with the constant C2
may vary over different temperature ranges.
06_07
, by the formula:
n
= ( v / ( 10mV / K ) ) - 273.15
o
is in C.
n
, which is displayed by the LDT-5525 Temperature Controller,
d
= C1 + ( C2 * T )
n
o
C over the rated operating
o
C is tolerable, no calibration of C1 or C2 is
C
C H A P T E R
o
C, with the error
o
C is
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LDT-5525