ILX Lightwave LDT-5500B Series User Manual page 67

The LDT-5500B Series Temperature Controller uses v to determine the nominal
temperature, T
T
n
- where T
The temperature, T
Controller, is first calibrated as follows:
T
d
- where C1 and C2 are the constants stored by the user in the LDT-5500B Series
Temperature Controller for the LM335.
When the LDT-5500B Series 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
operating range. With C1 and C2 calibrated also, the temperature accuracy is
typically +0.3
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
with the error 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.
05_11
, by the formula:
n
= (v / (10mV / K)) - 273.15
o
is in C.
n
, which is displayed by the LDT-5500B Series Temperature
d
= C1 + (C2 * T )
n
o
C over the rated operating range. The temperature accuracy may
o
C is tolerable, no calibration of C1 or C2 is
C H A P T E R
o
C over the rated
o
C,
o
C is
LDT-5500B Series
C
53
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