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26

WTC3243 TEMPERATURE CONTROLLER

RESISTIVE HEATER TEMPERATURE CONTROL

The WTC3243 can operate resistive heaters by disabling 

the cooling output current. When using Resistive Heaters 

with NTC thermistors, connect LIMA (Pin 3) to GND (Pin 13) 

with a 1.5 kΩ resistor.

Connect  LIMB  (Pin  4)  to  GND  (Pin  13)  with  a  1.5  kΩ 

resistor when using RTDs, LM335 type, and AD590 type 

temperature sensors with a resistive heater.

DETERMINE I

BIAS

The resistance of your sensor in conjunction with the sensor 

bias current must produce a setpoint voltage between 

0.25 V and (V

DD

 - 2 V) in order to be used in the control 

loop. 

Equation 6 

shows the relationship.

•  Connect a resistor R

BIAS

 between BIAS (Pin 10) and V

DD

 

(Pin  1) to set the sensor bias current. 

•  The LM335 always uses a 10 mA bias current (see 

Table 8 

for conversion equation).

Equation 6. 

Calculating I

BIAS

I

BIAS

 =   

      V

SET

  

 

   Sensor Resistance

   

 

    

  

  

SET THE SENSOR BIAS CURRENT AND SENSOR 
GAIN RESISTORS

Table 10 

lists the suggested resistor values for R

BIAS

 and R

G

 

for various sensors and resistance values. 

Equation 7 

demonstrates how to calculate a value of R

BIAS

 

given a desired sensor bias current, I

BIAS

.

Equation 7. 

Calculating R

BIAS

R

BIAS

 =   

     2  

[

]

  

 

        I

BIAS

   

 

    

  

  

Table 10.  Resistor Value and Resistance Range

SENSOR TYPE

I

BIAS

R

BIAS

SENSOR 

GAIN

R

G

2.252 kΩ Thermistor

1 mA

2 kΩ

1

Open

5 kΩ Thermistor

200 µA

10 kΩ

1

Open

10 kΩ Thermistor

100 µA

20 kΩ

1

Open

20 kΩ Thermistor

50 µA

40 kΩ

1

Open

50 kΩ Thermistor

20 µA

100 kΩ

1

Open

100 kΩ Thermistor

10 µA

200 kΩ

1

Open

500 kΩ Thermistor

2 µA

1 MΩ

1

Open

100 Ω Platinum 

RTD

1 mA

2 kΩ

10

Short or 

100 Ω *

1 kΩ Platinum RTD

1 mA

2 kΩ

1

Open

LM335

1 mA

2 kΩ

1

Open

R

GAIN

AD590

10 kΩ

Open

1

Open

* Sensor Gain with 100 Ω is exactly 10.  Sensor Gain shorted is 10.09.

When using RTDs, signal can be very low. The sensor signal 

applied to S+ (Pin 9) can be amplified up to a factor of 10 by 

inserting a resistor, R

G

, between SG (Pin 8) and GND (Pin 13). 

Connect SG (Pin 8) directly to GND (Pin 13) for a sensor gain 

of 10.09. The lower the value of R

G

, the more gain applied to 

the sensor signal.

Equation 8 

demonstrates how to calculate a value for R

G

 

given a desired sensor gain.

Equation 8. 

Calculating R

G

R

G

 = 

(

   

90,900     

-  10,000 

[

]  

 

   (G

SENSOR

 - 1)

   

 

    

  

  

Содержание WTC3293

Страница 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...

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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