© 2022
18
WTC32ND TEMPERATURE CONTROLLER
CONNECT THE TEMPERATURE SENSOR AND
THERMAL LOAD OR A TEST LOAD
With the ENABLE switch set to OFF (output is disabled),
connect the load (the thermoelectric cooler or resistive
heater) to the outputs (OUTA or OUTB). Use
to
determine the connections to the outputs.
Table 7.
OUTA & OUTB Wiring Configuration
SENSOR TYPE
LOAD TYPE
OUTPUT A
(OUTA)
OUTPUT B
(OUTB)
NTC Thermistor
Thermoelectric
Negative TEC
Terminal
Positive TEC
Terminal
100 Ω Platinum
RTD, LM335,
AD590
Thermoelectric
Positive TEC
Terminal
Negative TEC
Terminal
NTC Thermistor
Resistive Heater
Quick Connection:
Connect
the resistive heater to OUTA
and OUTB. Adjust the cooling
current limit to zero by turning
the LIMA trimpot fully CCW.
Maximum Voltage
Connection:
Connect one side
of the heater to OUTB and the
other to the voltage source V
S
.
100 Ω Platinum
RTD, LM335,
AD590
Resistive Heater
Quick Connection:
Connect
the resistive heater to OUTA
and OUTB. Adjust the cooling
current limit to zero by turning
the LIMB trimpot fully CCW.
Maximum Voltage
Connection:
Connect one side
of the heater to OUTA and the
other to the voltage source V
S
.
Resistive temperature sensors and LM335 type temperature
sensors should connect their negative termination directly
to Pin 13 (GND) to avoid parasitic resistances and voltages
affecting temperature stability and accuracy.
Connect thermistors and RTD sensors, which are not
polarized, to SEN+ and SEN- on Terminal Block 4 (TB4).
Connect LM335 and AD590, which are polarized, as shown
below.
LM335
SEN+
SEN-
AD590
V
DD
SEN+
SEN-
10 k
Ω
Figure 14. Connecting IC Temperature Sensors
MONITOR THE SETPOINT TEMPERATURE AND
ACTUAL TEMPERATURE SENSOR VOLTAGE
Terminal Block 3 (TB3) includes three lines for externally
monitoring the WTC32ND temperature setpoint voltage
(SET T) and the actual temperature sensor voltage levels
(ACT T). Both the SET T and ACT T voltages are measured
from the COMMON (COM) terminal.
Convert the monitor voltages to sensor resistance for
thermistors and RTDs, and to temperature for LM335s and
AD590s using the following equations.
Table 8. Converting the SET T and ACT T Monitor Voltages
SENSOR TYPE
VOLTAGE CONVERSION
Thermistor
100 Ω Platinum RTD
(where Sensor Gain is 10)
LM335 or AD590
* Voltage refers to the measurements made from the
ACT T or SET T points, in Volts (V). Sensor Bias Current
is in Amps (A).
Figure 15. WTC32ND-EV Evaluation Board & Voltmeter
To read the ACT T, attach the voltmeter to the ACT T and
COM wires.
To read the SET T, attach the voltmeter to the SET T and
COM wires.
R =
(
Voltage*
)
[
Ω
]
Sensor Bias Current
R =
(
Voltage*
)
/ 10 [
Ω
]
Sensor Bias Current
T = (Voltage* - 2.7315) * 100 [ºC]
USE
WITH
WTC Series
Temperature
Controller
ONLY
WAVELENGTH
ELECTRONICS
DMM
WTC32ND-EV EVAL BOARD
