Ite Current Calibration - ILX Lightwave LDT-5500B Series User Manual

ITE Current Calibration

The following procedure is for calibrating the ITE constant current source for both
polarities of current. During this procedure the ITE current is driven to a series of
pre-determined values. When each of these values is reached and is stable, the
user enters the actual value of the current, as measured by an external DMM. The
LDT-5500B Series Temperature Controller then automatically calibrates the TEC
current source and limits.
Calibration may be aborted by pressing the OUTPUT switch.
05_11
M A I N T E N A N C E A N D T R O U B L E S H O O T I N G
a For the LDT-5525B, connect a 1, 20W resistor across the TEC output terminals
(pins 1 and 3). For the LDT-5545B, connect a 1.5, 50W resistor. Use a calibrated
DMM to measure the voltage across the resistor. Calculate the current in the
following steps by using Ohm's Law: 

I = E / R

-where E is the accurately measured voltage across the resistor, and R is the
accurately measured load resistance. A 4-point probe resistance measurement is
recommended.
b Enter the calibration mode by pushing the display SELECT and mode SELECT
buttons. This will put the LDT-5500B Series into ITE calibration mode. Wait for three
seconds for the output to settle to about 3 Amps (LDT-5525B); 4 Amps (LDT-5545B).
c Press and hold in the ENABLE button and turn the ADJUST knob until the display
shows the correct value (absolute value of the ITE measurement, as calculated from
Step a).
d Release the ENABLE button. Wait three seconds to allow the ITE current to settle at
the new set point.
e Repeat Steps c and d for all six set points, once for each of the (automatically
adjusted) set points. For the LDT-5525B, the set points are: 3A, -3A, 3A, 1A, -1A, and
-3A. For the LDT-5545B, the set points are: 4A, -4A, 4A, 1A, -1A, and -4A.

After the last set point is entered, the LDT-5500B Series Temperature Controller's
front panel will go blank while the instrument calibrates the ITE set point and current
limits. Allow the instrument to self calibrate. Once completed, the calibration
constants will be stored to non-volatile memory, and the display will return to its
previous state.
f After calibration, the I LIMIT will be automatically set to 2.00 Amps. Reset the I LIMIT
to the desired value.
Calibration Adjustments
LDT-5500B Series
5
C H A P T E R
41
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