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11
FL591FL LASER DIODE DRIVER
TROUBLESHOOTING
PROBLEM
POTENTIAL CAUSES
SOLUTIONS
Driver will not switch on
Improperly configured power
supply
Carefully check the wiring diagram on
page 2
. Make sure the power
supply polarity is not reversed.
Power supply voltage too low
Check the electrical specifications on
page 6
and make sure the power
supply is within the required voltage range to operate the FL591FL.
Output will not enable
Improperly configured Enable
switch on the FL591FL
The DIS pin on the Power connector must be grounded AND the switch on
the FL591FL must be set to ENABLE.
Power supply voltage too low
Check the electrical specifications on
page 6
and make sure the power
supply is within the required voltage range to operate the FL591FL.
Driver not working properly
in constant current, parallel-
output mode
Jumpers configured incorrectly
Check
page 9
to make sure the output jumper is set properly.
Improper output wiring
configuration
Check that the connections to the laser diode are made via output
connector LD1.
Laser output power too low
in Constant Current mode
Laser current setpoint too low
Increase the setpoint either by adjusting the trimpot, or by increasing the
signal voltage on the input connector.
Laser current limit too low
Refer to
page 9
for instructions on setting the laser driver current limit.
Laser driver is compliance limited
Check the laser diode specifications to determine the forward voltage
(V
F
). Make sure that the FL591FL is not compliance limited. Refer to the
Electrical Specifications table on
page 6.
Laser does not reach desired
output in Constant Power
mode
Current limit too low
Check the laser diode datasheet to determine the approximate laser drive
current at the desired optical power output level. Then verify that the current
limit is set slightly higher than that. Refer to
page 9
for instructions on
setting the laser driver current limit.
Photodiode feedback current is
out of range for the FL591FL
Refer to
page 12
for information on adjusting the photodiode current
range.
