WCB201 datasheet(25/28 Pages) WAVELENGTH

25 / 28 page

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LDD P 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 1 or Table 2,

depending on model.

Pins 3 and 4 not shorted

Laser output power too

low

Laser current setpoint too low

Increase the setpoint either by adjusting the OUTPUT ADJUST

trimpot clockwise, or by decreasing the signal voltage on MOD

INPUT (pin 3).

Laser current limit too low

Refer to

page 11 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 LDD P is not compliance limited.

Refer to the Electrical Specifications table on

page 5. If the

driver is compliance limited, V+ may need to be increased.

Verify that the LDD P will be operating within the Safe Operating

Area if V+ is increased.

Modulation is not working

Laser current setpoint is too

low

Modulation input on the LDD P is accomplished by subtracting from

the laser setpoint. If the current setpoint is too low, the modulation

can drive the current to the laser to zero. If the current setpoint is set

to zero, no modulation is allowed.

WCB201 Datasheet(PDF) 25 Page - Wavelength Electronics, Inc.