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WLD3393
PAGE 7
WLD3393-00400-K
VS+VDD
VSET
SOURCE
T
X
PD RANGE
2 mA
200
P
A
LD
RANGE
200 mA
2 Amp
STEP 3: CONFIGURE JUMPERS
Jumper positions are shown in Figure 4. Factory default locations are noted.
LD CURRENT RANGE & PD CURRENT RANGE
The two modes of operation supported by the WLD3393 are constant current and constant power
mode.
It is very important to note that the WLD3393 should be confi gured for either constant
current or constant power mode BEFORE power is applied. Changing operating mode while the
WLD3393 is operating can result in damage to your laser diode.
In constant current mode, VSET
correlates directly to the laser diode current, regardless of laser diode power intensity. In constant
power mode, the WLD controls the laser diode using the photodiode to achieve a laser intensity that
is directly proportional to VSET.
Constant Current mode
ignores the laser’s photodiode. The WLD3393, however, is designed
to allow you to monitor the laser’s photodiode while running in this mode. Monitor the voltage at
the PDM pin on the terminal block on the top side of the WLD3393. Before powering the unit on
to operate in constant current mode, make sure that the Mode Switch is in the CC position (see
Figure 1). Select the output current range by setting the LD RANGE jumper on the back of the
WLD3393 to either the 200 mA or the 2 A position.
Constant Power mode
utilizes the laser’s photodiode to regulate the intensity of the laser in
proportion to VSET. While the unit is NOT powered, make sure the Mode Switch is in the CP
position to con
fi
gure the WLD3393 for constant power mode (see Figure 1). Set the PD RANGE
jumper on the bottom of the WLD3393 to either the 200
A or the 2 mA range, depending on the
speci
fi
cations of your photodiode. See Figure 4 for the location of the PD Current Range jumper.
It is important to make sure that the correct PD current range is selected as the WLD3393 may
overdrive the laser if the PD range is con
fi
gured incorrectly, resulting in permanent damage to
the laser. Use the LD RANGE jumper to select between the 200 mA and 2 A range based on
the rating of the laser load.
POWER SELECT JUMPER
The factory default is to separate the V
S
and V
DD
power supply inputs. V
S
drives the laser diode while
V
DD
powers the control electronics. You can tie these together instead by moving the Power Select
Jumper to the “
V
S
+ V
DD
”
position. Note that when in this position, V
S
on the input connector pin will be
at the same potential as the V
DD
pin.
VSET SOURCE JUMPER
The factory default is to use the onboard setpoint trimpot to generate the setpoint voltage (“
T
” position).
To use an external signal, move this jumper to the “
X
” position.
Figure 4: Bottom View, Jumper Locations -- Factory Default
VSET SOURCE JUMPER
(use onboard setpoint
trimpot shown)
LD RANGE JUMPER
(200 mA shown)
PD RANGE JUMPER
(200
A shown)
POWER SELECT JUMPER
(separate supplies shown)
CONFIGURING THE EVALUATION BOARD
