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TROUBLESHOOTING
PROBLEM
Driver will not switch on
Output will not enable
Laser output power too
low in Constant Current
mode
Laser does not reach
desired output in
Constant Power mode
Modulation is not working
Cannot zero the trimpots
Photodiode feedback is
inaccurate
Transfer functions are
inaccurate
© 2018
POTENTIAL CAUSES
Improperly configured power
supply
ENABLE pin not held low
Laser current setpoint too low
Laser current limit too low
Laser driver is compliance
limited
Photodiode feedback current
is out of range for the WLD
V
improperly configured
SET
Improperly configured R
or
PD
PD RANGE jumper
Improperly configured
CC/CP Mode
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WLD SERIES LASER DIODE DRIVERS
Standalone: Carefully check the wiring diagram according to
page 13 and page 14.
Evaluation Board: See page 18 for details regarding power supply
connections.
Standalone: Refer to the SHD pin specifications in Table 1 and
make sure this pin is held at zero volts or left floating.
Evaluation Board: Ensure that the ENABLE switch is fully rockered
to the ON position.
Increase the setpoint by increasing the voltage at Pin 2 (V
Evaluation Board: The setpoint can be increased using the onboard
SET trimpot, and/or using the SET input on the terminal strip.
Standalone: Refer to page 11 for instructions on setting the laser
driver current limit.
Evaluation Board: Refer to page 19 for instructions on setting the
laser driver current limit.
Check the laser diode specifications to determine the forward
voltage (V
). Make sure that the WLD is not compliance limited.
F
Refer to the Electrical Specifications table on page 6. If the
driver is compliance limited, V
Verify that the WLD will be operating within the Safe Operating
Area if V
is increased.
DD
Refer to the laser diode datasheet to determine the approximate
photodiode (PD) current at the desired output power level. If the PD
current exceeds the chosen WLD photodiode current range, either:
Standalone: see page 12 for instructions on how to properly set
the photodiode current range by choosing R
Evaluation Board: see page 17 for instructions on how to increase
the PD RANGE jumper value.
Standalone: See page 15 for details for modulating using V
Evaluation Board: See page 20 for proper evaluation board
configuration for modulation.
Evaluation Board: The trimpots that are installed on the
WLD3393 are 12-turn trimpots. This means that after 12 full turns
counterclockwise, they will be set to zero, even though they will turn
continuously.
Standalone: see page 12 for instructions on how to properly
choose the photodiode current range by choosing R
Evaluation Board: see page 17 for instructions on how to change
the PD RANGE jumper value.
If CC/CP Mode is improperly configured, this can lead to
inaccuracies in the transfer functions.
Standalone: See page 13 or page 14 for proper wiring
diagrams.
Evaluation Board: Make sure the MODE switch is fully rockered to
the desired operating mode.
SOLUTIONS
may need to be increased.
DD
.
PD
.
PD
).
SET
.
SET
25
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