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19

PLD SERIES LASER DIODE DRIVER

TROUBLESHOOTING

PROBLEM

POTENTIAL CAUSES

SOLUTIONS

Driver will not switch on

Improperly configured power

supply

Carefully check the wiring diagram according to

Table 3.

Output will not enable

Remote Enable signal is not

correct

Refer to the LD Enable specifications in

Table 1 and make sure your

input enable signal is correct.

Laser output power too

low in Constant Current

mode

Laser current setpoint too low

Increase the setpoint either by adjusting the I SET trimpot clockwise,

or by increasing the signal voltage on the Analog Input (pin 9).

Laser current limit too low

Refer to

page 12 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

to the Electrical Specifications table on

page 6. If the driver is

compliance limited, V

the PLD will be operating within the Safe Operating Area if

V

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. See

page 12 for

instructions on setting the laser driver current limit.

Photodiode feedback current

is out of range for the PLD

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 PLD PD current range, set the PD Range switch

to High Range; see

page 12.