background image

© 2022

www.teamWavelength.com

21

WTC3243 TEMPERATURE CONTROLLER

OPERATING WITH THERMISTOR TEMPERATURE SENSORS

A thermistor sensor has the best sensitivity, very small size, a temperature 

range of -80º to +150º C, but poor linearity. 

Thermistor temperature sensors should connect one terminal as close 

as possible to GND (Pin 13) to avoid parasitic resistances and voltages 

affecting temperature stability and accuracy.

The diagrams on this page demonstrate how to configure the WTC3243 for 

operation with a thermistor temperature sensor. An online calculation utility 

to determine resistances is available at: 

www.teamwavelength.com/support/design-tools/wtc-calculator/

.

Figure 16.  Thermistor / TEC Operation -- Top View

Figure 17.  Thermistor / Resistive Heater Operation -- Top View

IF YOU ARE UPGRADING FROM THE WHY5640: The position of Pin 1 on the WHY5640 is reversed (or mirrored) relative 

to the position of Pin 1 on the WTC3243.

V

S

V

DD

TIE GROUND CONNECTIONS DIRECTLY TO PIN 13

1

WTC3243

Temperature

Controller

1
2

3
4
5
6
7

14
13

12
11
10

9
8

Actual 

Temperature

Monitor voltage

V

DD

R

T

R

BIAS 

R

R

P

 

R

LIMA

R

LIMB

Adjusting PI

Control Loop

Adjusting Limit

Currents

V

SET

VSET = Sensor Resistance X Sensor Bias Current

1

1

-

+

TOP VIEW

NC

OR

D/A

V

DD

Bandgap

Voltage

Reference

W

CCW

OR

QUICK CONNECT LEGEND

DIAGRAM 

REFERENCE

TABLE OR EQUATION

R

LIMA

Table 9 on page 25

R

LIMB

Table 9 on page 25

R

P

Table 11 on page 27

R

I

Table 12 on page 27

R

BIAS

Table 10 on page 26

Equation 6

 & 

 Equation 7

R

T

Thermistor datasheet

R

G

N/A

V

S

V

DD

TIE GROUND CONNECTIONS DIRECTLY TO PIN 13

1

WTC3243

Temperature

Controller

1
2

3
4
5
6
7

14
13

12
11
10

9
8

Actual 

Temperature

Monitor voltage

V

DD

R

T

R

BIAS

 

R

R

1.5 k

R

LIMB

Adjusting PI

Control Loop

Adjusting Limit

Currents

V

SET

VSET = Sensor Resistance X Sensor Bias Current

1

1

NC

V

S

TOP VIEW

NC

V

DD

Bandgap

Voltage

Reference

W

CCW

OR

OR

D/A

Summary of Contents for WTC3293

Page 1: ...ATIONS The robust and reliable WTC3243 has been designed into electro optical systems airborne instrumentation spectroscopic monitors and medical diagnostic equipment It is particularly well suited to...

Page 2: ...rminethattheunitwillbeoperatingwithinthe internalheatdissipationSafeOperatingArea SOA Visit the Wavelength Electronics website for the most accurate up to date and easy to use SOA calculator www teamw...

Page 3: ...ge 25 Control Parameters PGAIN Table 5 on page 14 Equation 1 RP Table 11 on page 27 I TERM Table 5 on page 14 Equation 3 RI Table 12 on page 27 Bias Current Sensor Bias Switch Table 4 on page 13 Figur...

Page 4: ...Gain Remove R8 and load R54 I TERM To set a Fixed I Term Remove R13 and load R55 TP7 TP4 TP3 TP5 CW W CCW R5 200K TP6 C5 0 1UF C6 0 1UF R50 N L R51 N L Set T To set a Fixed Set point Voltage Remove R...

Page 5: ...peration requires that VDD be 8 V or greater 10 BIAS Sensor Bias Current Resistor Connection Connect a resistor between BIAS Pin 10 and VDD Pin 1 to configure the sensor bias current 11 OUTA Thermoele...

Page 6: ...y input for output stage Directly connected to WTC3243 VS Pin 14 PGND Power Ground Directly connected to WTC3243 GND Pin13 Terminal Block 2 TB2 Auxiliary Terminal Block FAN Fan Positive Red wire conne...

Page 7: ...ET to Sensor Voltage 1 V V The controller drives the TEC or heater to make the voltage across the sensor match the RSET voltage SET T Monitor to VSET 1 V V The setpoint temperature monitor voltage mat...

Page 8: ...VS 1 0 Volts Full temp range IOUT 2 2 A Short Term Stability 1 hour 0 0009 C OFF ambient temperature TSET 25 C using 10 k thermistor 1 Short Term Stability 1 hour 0 002 C ON ambient temperature TSET 2...

Page 9: ...ude the tolerance of the bias current resistor THERMAL Heatspreader Temperature Rise 28 to 33 C W TAMBIENT 25 C Heatspreader Temperature Rise 18 to 25 C W With WHS302 Heatsink WTW002 Thermal Washer He...

Page 10: ...put voltage range 0 6 5 VSET X 0 2 5 VSET T Volts X is the external setpoint jumper T is the internal trimpot jumper ACT T MON output voltage range 0 to VDD Volts Limited by bias current circuit 1 Sen...

Page 11: ...easures the load temperature by driving a current through the temperature sensor and measuring the voltage drop across it It may be useful to remember that you do not directly adjust the setpoint temp...

Page 12: ...operation WTC3243 Temperature Controller WTC3293 PCB evaluation board Digital multimeter 4 digit resolution recommended Thermistor or other temperature sensor Peltier type thermoelectric module or res...

Page 13: ...T is Source Trimpot is Source Factory Default Figure 7 VSET Source Jumper Settings SET THE SENSOR BIAS SWITCH Use Table 4 to configure the evaluation board for your temperature sensor type Sensor sign...

Page 14: ...not match the table if the WTC3243 is installed P GAIN I TERM Figure 10 Location of the P GAIN and I TERM Trimpots Table 5 suggests starting points for P GAIN and I TERM depending on your sensor type...

Page 15: ...ATION BOARD The notch at the top of the WTC3243 must be orientedatthetopofthePrintedCircuitBoard PCB ThisorientationplacesPIN1intheupper left corner See Figure 11 below for proper orientation USE WITH...

Page 16: ...d on the WTC so the location of the wires matches your PCB Screw 4 40 PHPH x 0 75 w o FAN x 1 with FAN 30 mm FAN WXC303 5 VDC or WXC304 12 VDC WHS302 Heatsink WTW002 Thermal Washer WTC3243 Heat Spread...

Page 17: ...tion The 2 5 mm input power jack is attached to VDD You can use the Wavelength PWRPAK power supplies with this jack Use either the power jack or the power inputs on TB1 not both TheCOMMON COM terminal...

Page 18: ...gative 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 an...

Page 19: ...mpot can be adjusted from 0 V to 5 V To get above 4 5 V increase VDD to a minimum of 5 5 V To read the actual temperature and setpoint temperature of the device the power needs to be connected NOTE If...

Page 20: ...arts are included in this datasheet for quick reference but we recommend you use the online tools instead Refer to the SOA calculator for the WTC3243 www teamwavelength com support design tools soa tc...

Page 21: ...on the WHY5640 is reversed or mirrored relative to the position of Pin 1 on the WTC3243 VS VDD TIE GROUND CONNECTIONS DIRECTLY TO PIN 13 1 WTC3243 Temperature Controller 1 2 3 4 5 6 7 14 13 12 11 10...

Page 22: ...ual Temperature Monitor voltage VDD RT RTD RBIAS RI RP RLIMA RLIMB RG Adjusting PI Control Loop Adjusting Limit Currents VSET VSET Sensor Resistance X Sensor Bias Current X 10 for 100 RTDs 1 1 1 NOTE...

Page 23: ...5640 The position of Pin 1 on the WHY5640 is reversed or mirrored relative to the position of Pin 1 on the WTC3243 TOP VIEW VS VDD TIE GROUND CONNECTIONS DIRECTLY TO PIN 13 1 WTC3243 Temperature Contr...

Page 24: ...or mirrored relative to the position of Pin 1 on the WTC3243 TOP VIEW VS VDD TIE GROUND CONNECTIONS DIRECTLY TO PIN 13 1 WTC3243 Temperature Controller 1 2 3 4 5 6 7 14 13 12 11 10 9 8 Actual Temperat...

Page 25: ...Figure 25 shows fixed heating and cooling limits and is the standard implementation Figure 25 Fixed Heat and Cool Current Limits Figure 26 diagrams setting current limits independently using trimpots...

Page 26: ...or values for RBIAS and RG for various sensors and resistance values Equation 7 demonstrates how to calculate a value of RBIAS given a desired sensor bias current IBIAS Equation 7 Calculating RBIAS RB...

Page 27: ...ion 10 Calculating PGAIN from RP PGAIN 100 A V 100 000 1 RP SET THE CONTROL LOOP INTEGRATOR TIME CONSTANT To set the control loop Integrator Time Constant ITC insert a resistor RI between 1V Pin 6 and...

Page 28: ...CW terminal to the pin marked COM Do not use less than 2 k resistance or the 2 5 V will droop FAN REN HSET COM W CW CCW 2 5 V TB2 SET T ACT T LIMA LIMB COM RSET TB3 Figure 28 Example Wiring External R...

Page 29: ...43 installed Measure the PGAIN trimpot value across pins TP5 TP6 Remove resistor P2 Load P1 with a resistor of the value measured 1206 size BOTTOM VIEW RESISTOR LOCATIONS TOP VIEW TEST POINT LOCATIONS...

Page 30: ...LB2 and LB1 and TP4 TP1 respectively TOP VIEW TEST POINT LOCATIONS BOTTOM VIEW RESISTOR LOCATIONS Figure 32 LIMA LIMB Settings CHANGING ONBOARD SETPOINT TRIMPOT TO A FIXED RESISTANCE Connect an ohmme...

Page 31: ...ller VDROP VS VMAX VS is the power supply voltage Mark VDROP on the X axis and extend a line upward Mark IMAX on the Y axis and extend a line to the right until it intersects the VDROP line On the X a...

Page 32: ...mponents of the thermal load Use thermal paste or washers between the load TEC and the TEC heatsink interfaces Ensure the temperature sensor is in good thermal contact with the load Unit may be operat...

Page 33: ...ase the current limit but DO NOT exceed the specifications of the TEC or heater The WTC3293 is not producing current The P GAIN or I TERM may be turned all the way counter clockwise CCW Turn the P GAI...

Page 34: ...00 2 54 1 30 33 0 0 20 5 1 1 26 32 0 0 33 1 28 32 5 0 945 24 00 0 945 24 00 2 PLS 4 40 UNC WTC3243 0 125 3 18 Thru 0 25 6 4 DIA KEEPOUT 4 Required 0 038 0 97 Dia Thru Hole 0 060 1 52 Dia Pad 14 Requir...

Page 35: ...19 4 83 1 880 47 75 57 15 2 25 0 19 4 83 0 17 4 32 2 42 61 47 0 13 3 3 THRU 4 PLS All dimensions are inches mm All tolerances are 5 Direction for Recommended Airflow Weights WTC3293 WTC3243 1 6 oz WHS...

Page 36: ...ion contained in this document is subject to change without notice Wavelength will not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishin...

Reviews: