© 2018
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LDTC2/2 LASER DIODE DRIVER AND TEMPERATURE CONTROLLER
OPERATING INSTRUCTIONS –
LASER DRIVER
!
Operate the LDTC2/2 with all loads attached.
If you short either the LD or TC output
connections during setup, current will flow
and possibly overheat/damage the WLD or
WTC.
RECOMMENDED ORDER OF SETUP
WTC configuration should be addressed first, using a
simulation diode load in place until the temperature control
section is working properly. After the temperature control
section is operating according to preferences, then the
laser diode load can be configured. Using a simulated diode
load until you are comfortable with WLD configuration and
operation is recommended in order to avoid any potential
damage to an expensive laser diode.
CHOOSE OPERATING MODE – CONSTANT
CURRENT OR CONSTANT POWER
A sliding switch selects operating mode.
!
Do not move the CC/CP switch while power is
applied, or you risk damaging or destroying
your laser diode.
In Constant Current mode, Laser Diode I
SET
correlates
directly to the laser diode current, regardless of laser diode
power intensity.
In Constant Power mode, the LDTC2/2 controls the laser
diode using the photodiode to achieve a laser light intensity
that is directly proportional to Laser Diode I
SET
.
Select the mode of operation for the LDTC2/2 with the power
off by setting the sliding switch to the CC position for Constant
Current mode, or the CP position for Constant Power Mode.
SELECT THE MONITOR PHOTODIODE CURRENT
RANGE (CONSTANT POWER OPERATION)
Select between two ranges on the LDTC2/2 board:
2.0 mA or 200 μA. A jumper (PDset) selects the range. Move
this jumper only when power is not applied to V
DD
.
Setting for
2.0 mA range
Setting for
200 µA range
CC
CP
CC
CP
ExtTset Vset
PDset
Vset
PDset
ExtTset
Figure 8. Select the photodiode range with the PDset
jumper.
The transfer function of the setpoint voltage depends on
this setting for Constant Power Operation (see
). If you choose the wrong setting, you could
overdrive your laser diode.
If you would prefer a different range, contact Wavelength.
POWER SUPPLY SELECTION
!
Online Safe Operating Area (SOA)calculators
are available for the LDTC2/2. Calculate the
maximum power dissipation of your design
before applying power to the LDTC2/2
.
The V
DD
voltage supply is common to both the WLD3343
and the WTC3243. This supply furnishes the voltage to the
control electronics of the devices as well as the compliance
voltage for the WLD3343 Laser Driver.
The supply should be capable of providing at least 3.0 A
of current in applications that use a separate V
S
supply
in the temperature control implementation. Temperature
control applications that tie V
DD
and V
S
together require a
V
DD
current capacity that equals the sum of the maximum
TEC or Resistive Heater current, plus the maximum laser
diode current, plus approximately 200 mA for the control
electronics of the WTC3243 Temperature Controller and the
WLD3343 Laser Driver. Using the maximum potential of the
WLD and WTC will not require more than 6.0 A.
Performance of the laser driver is very dependent upon
the performance of the power supply. The LDTC2/2 does
provide some filtering of the power supply input. For
optimal performance, a power supply that can provide the
appropriate level of noise and ripple for the application at
hand should be utilized.
Wavelength Electronics offers a selection of switching power
supplies in a range of output voltage and current capacities.
