© 2005
PRELIMINARY
LDTC2/2
PAGE 9
LDTC2/2-00400-A Rev A
WTC OPERATION
Recommended order of setup:
WTC temperature control section WITHOUT
the laser diode installed THEN the WLD laser
diode driver. Use a simulated laser diode
load until you are comfortable with the WLD
operation.
1. CONFIGURING HEATING AND
COOLING CURRENT LIMITS
The LDTC2/2 has two trimpots that
independently set the heating and cooling
current limits: LIM A & LIM B. These are
12-turn 5k
Ω
trimpots. Full current (2.2 A)
is at full CCW position. Table 1 shows the
meaning of the trimpots with various sensors
and actuators. Note that PTC sensors include
100
Ω
platinum RTDs, the LM335, and the
AD590.
Table 1
Trimpot function vs. Sensor & Load Type
Sensor Type
Thermistor
PTC
Thermistor
PTC
Load Type
Thermoelectric
Thermoelectric
Resistive Htr
Resistive Htr
LIM A Limits:
Cool Current
Heat Current
Turn off -
Fully CW
Heat Current
LIM B Limits:
Heat Current
Cool Current
Heat Current
Turn off -
Fully CW
2. WIRE OUTPUT CONNECTION
Use Table 2 to determine the connection from
the LDTC2/2 to your thermoelectric or resistive
heater.
Sensor Type
Thermistor
PTC
Thermistor
PTC
Load Type
Thermoelectric
Thermoelectric
Resistive Htr
Resistive Htr
TEC+ Connector 3, Pin 6
Thermoelectric positive wire
Thermoelectric negative wire
TEC - Connector 3, Pin 7
Thermoelectric negative wire
Thermoelectric positive wire
Quick Connect:
Connect the Resistive Heater to TEC+ & TEC - (polarity doesn’t
matter). Adjust the Cooling Current Limit A trimpot to zero - fully CW.
Max V Connect:
Connect one side of the resistive heater to TEC- and the other
side to the voltage source V
S
. LIM A trimpot setting is then irrelevant.
Quick Connect:
Connect the Resistive Heater to TEC+ & TEC - (polarity doesn’t
matter). Adjust the Cooling Current Limit B trimpot to zero - fully CW.
Max V Connect:
Connect one side of the resistive heater to TEC- and the other
side to the voltage source V
S
. LIM B trimpot setting is then irrelevant.
Table 2
Wiring vs. Sensor & Load Type
3. CONNECT TEMPERATURE SENSOR
The LDTC2/2 is confi gured to operate a 10k
Ω
thermistor with a 100
µ
A bias current. If your
application requires a different sensor, please contact
Wavelength for details. Wire the thermistor between
pins 8 & 9 (SENS+ & SENS-) on Connector
J3. Operating without a temperature sensor will
drive maximum current through the WTC, potentially
damaging it.
CAUTION:
Operate the LDTC2/2 with loads attached -
if you short either the LD or TC output
connections during setup, current will fl ow and
possibly overheat / damage the WLD or WTC.
