ILX Lightwave LDC-3700B Series - Set Current Source Limit

OPERATIONS
Operating from the Front Panel
18 LDC-3700 Series
CHAPTER 2
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the laser drive current to exceed the limit independent of the set point and the controller mode
(Constant Current or Constant Power).
Set Current Source Limit
To set the current source limit, use the SELECT push button in the PARAMETER/LASER section of
the front panel to select LIM I. You will notice there are two LIM I selections, one in blue text and the
other in black text. The blue text limit selection corresponds to the blue text current source range as
indicated in the RANGE section. The LASER display will be indicating the limit set point in mA
indicated by the LIM I LED, for its corresponding range. Press and hold the (PARAMETER) SET
push button and rotate the adjust knob, clockwise to increase the limit set point value, or
counterclockwise to decrease the limit set point value. Set the limit to 175 mA. Once the SET push
button is released, the new parameter value is stored in non−volatile memory.
When the LASER current limit is reached, the CURRENT LIMIT error indicator flashes. The current
limit setting is independent of the voltage drop of the device connected to the LASER output, and
therefore, no dummy load is required for precise adjustment of the current limit. Furthermore, since
the current limit circuitry is fully independent of the main current control, the current limit can be
adjusted safely, even while the LASER output is active.
A new feature of the 3700B Series instruments is an adjustable voltage limit. This allows an extra
level of laser protection in the event of an intermittent open circuit. For maximum protection via the
fastest open−circuit detection, the voltage limit should be set to a value slightly greater than the
intended operating voltage.
To set the LASER voltage limit, use the SELECT push button in the PARAMETER/LASER section
of the front panel to select LIM I (either range) and then press and hold the (PARAMETER) SET
push button. Then press the LASER DISPLAY V push button. The LASER display will then indicate
the LASER voltage limit setting. While holding the (PARAMETER) SET push button, adjust the
voltage limit using the adjust knob.
In the LASER MODE section of the front panel, press the push button labeled OUTPUT. The
accompanying LED labeled ON will illuminate indicating that the laser current source’s output is
TEC
LAS
ADJUST
LIM I
TE
SAVE
CONST
GAIN
LIM T
HI
TEC
LIM I
CAL PD
LIM I
LIM P
RECA LL
SET
SELECT
PARA M ETER
LASE
R
LASER DISPLAY
II
PD
P
PD
V
SET
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