© 2018
17
WLD SERIES LASER DIODE DRIVERS
Step 3: Choose Operation Mode
The two modes of operation supported by the WLD3393 are
Constant Current (CC) and Constant Power (CP):
• In Constant Current mode, V
SET
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 V
SET
.
Prior to applying power to the board, use the Mode Switch
to choose either CC or CP. Ensure that the switch is
completely rockered to the chosen end.
!
It is very important to configure the
WLD3393 for the desired operation mode
before power is applied. Changing operation
mode while the WLD3393 is operating can
result in damage to your laser diode.
Step 4: Configure Jumpers
Jumper positions are shown in
. Factory default
locations are noted.
• LD RANGE Jumper:
Select the laser diode output
current range by using the LD RANGE jumper on the
back of the WLD3393. The two available options are
the “200 mA” or the “2 A” position.
• PD RANGE Jumper:
Set the PD RANGE jumper on
the bottom of the WLD3393 to either the “200 μA” or
the “2 mA” range, depending on the specifications
of your photodiode. It is important to make sure that
the correct PD current range is selected. If the wrong
range is chosen, the WLD3393 may overdrive the laser,
resulting in permanent damage to the laser.
• 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 “VS+VDD” 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.
VS+VDD
VSET
SOURCE
T
X
PD RANGE
2 mA
200
µ
A
LD
RANGE
200 mA
2 Amp
POWER SELECT JUMPER
(separate supplies shown)
LD RANGE JUMPER
(200 mA shown)
PD RANGE JUMPER
(200
μ
A shown)
VSET SOURCE JUMPER
(use onboard setpoint
trimpot shown)
Figure 15. Jumper locations (factory default), bottom view of WLD3393.
