© 2013
PAGE 8
WTC3293
www.teamwavelength.com
WTC3293-00400-I
STEP 7: CONNECTING YOUR THERMAL LOAD
Use Table 4 to determine how to connect the WTC3243 outputs (OUTA or OUTB) to your thermoelectric
or resistive heater.
CONFIGURING THE EVALUATION BOARD
Table 4 - Output Con
fi
guration
Load Type
Output A
Sensor Type
Output B
100
Platinum RTD,
LM335, AD590
Negative TE Terminal
Positive TE Terminal
Thermoelectric
Thermoelectric
Thermistor
Negative TE Terminal
Positive TE Terminal
Thermistor
Resistive Heater
Quick Connection
: Simply 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 resistive heater to OUTB and the
other side to the voltage source V
S
.
Quick Connection
: Simply 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 resistive heater to OUTA and the
other side to the voltage source V
S
.
100
Platinum RTD,
LM335, AD590
Resistive Heater
Thermistor and RTD sensors are not polarized, so connect between SEN+ and SEN- on Terminal
Block 4. For LM335 and AD490, connect as shown in Figure 8 below.
Figure 8
Connecting IC Temperature Sensors
V
DD
SEN+
SEN-
SEN+
LM335
AD590
Table 5 - Converting the SET T and ACT T Monitor Voltages
STEP 8: MONITORING THE TEMPERATURE SETPOINT VOLTAGE AND ACTUAL TEMPERATURE
SENSOR VOLTAGE
Terminal Block 3 (TB3) includes three lines for externally monitoring the WTC3243 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 terminal (COM).
Use Table 5 to convert these monitor voltages to sensor resistance for thermistors and RTDs or
temperature for the LM335 and AD590.
* Voltage refers to the
measurements made from the
ACT T or SET T points, in volts.
Sensor Bias Current is in amps.
Sensor Type
Thermistor
100
Platinum RTD
(where GAIN is 10)
LM335 or AD590
Voltage Conversion
R=
Voltage*
Sensor Bias Current
T= (Voltage* - 2.7315) * 100
C
R=
Voltage*
Sensor Bias Current
/10
