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LDTC0520 / LDTC1020
PAGE 11
LDTC1020-00400-A Rev B
WTC OPERATION
Recommended order of setup:
First complete the WTC temperature control
section THEN confi gure the laser diode driver.
Use a simulated laser diode load until you are
comfortable with the laser driver operation.
1. CONFIGURING HEATING AND
COOLING CURRENT LIMITS
The LDTC 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 Counter-Clockwise
(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 LDTC to your thermoelectric or resistive
heater.
Sensor Type
Thermistor
PTC
Thermistor
PTC
Load Type
Thermoelectric
Thermoelectric
Resistive
Heater
Resistive
Heater
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 leads 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 leads 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 for Sensor & Load Type
3. CONNECT TEMPERATURE SENSOR
The standard LDTC is confi gured to operate a
10k
Ω
thermistor with a 100
μ
A bias current. If
your application requires a different sensor, see
page 12 for details. Wire the thermistor between
pin 8 (SENS+) and pin 9 (SENS-) on Connector
J3. Operating without a temperature sensor will
drive maximum current through the WTC, potentially
damaging it.
CAUTION:
Operate the LDTC with loads attached - if you
short either the LD or TC output connections
during setup, current will fl ow and possibly
overheat / damage the laser diode driver or
temperature controller.
