TEC-8A-24V-PID-HC-RS232 Programmable Temperature Controller

About the TEC-8A-24V-PID-HC-RS232 Programmable Temperature Controller

TEC-8A-24V-PID-HC-RS232 Programmable Temperature Controller is an improved digital temperature controller with the possibility to change parameters and read them using UART port.

The new version is able to heat and cool without changing any jumpers. It has also open collector output which allows to use it as a signal for other devices. Additional LED diodes show heating or cooling activity. Also, the dimensions of the PCB are smaller and the mounting holes have been added.

Its small size, the simplicity of regulation and versatility make it widely used in many areas. It is dedicated to working with 12 V thermocouples (Peltier modules) yet it does well with all modules whose supply voltage falls in the range of 5 to 24 V.

The controller operates in PWM mode (Pulse Width Modulation) and can control currents of up to 8 A. For the temperature sensor, it uses a standard 10 k NTC thermistor. By default, the temperature setpoint is set to 20 degrees Celsius.

Due to the possibility to set the parameters of a PID controller, the driver can be adapted to almost any system. Depending on the inertia of the system, a properly adjusted driver is able to maintain the desired temperature with an accuracy of up to +- 0.05*C.

In normal work (when SJ1 jumper is not shorted/soldered), you can use UART port to read the temperature setpoint, actual temperature, and PID parameters values. To this end just use the GND, TXD and RXD outputs. To read the proper value of the temperature you have to use a thermistor with a BETA value of 3950. Adjustment is made with the use of four trimmers. Trimmers allow to set P I D parameters, as well as to set temperature working point.

When SJ1 is soldered/shorted user gets control on the regulator. Using PC and USB -> RS232 TTL it is possible to send and read parameters to/from the regulator. To this end just use the GND, TXD and RXD outputs. To read the proper value of the temperature you have to use the thermistor with the BETA value of 3950 which is also included with the driver. While using this mode, trimmers are not working, but the user gets full control of any of the parameters. Additionally, it is possible to set a lower/upper threshold which is checking by the driver (OC). Setting these parameters to ensure that the device will be working in a certain range of temperature.

TXD should be connected to RXD, RXD should be connected to TXD, GND should be connected to GND.

The current flowing through the Peltier cell depends on the supply voltage used. Most of the common modules should be supplied with the voltage of 12 to 15 V, and the maximum current that flows through them is defined by a cell symbol. For example, the 12708 symbol means that the cell should be supplied with the voltage of 0 to 12 V, and a maximum current which can be used amounts to 8 A.

Recommendations and requirements

We recommended the use of power cables with a minimum cross-section of 0.5 mm2.

Protection

The system detects a lack of connection with a thermistor and then switches WARNING LED on. As long as the connection is lost, the driver will not take any action and the open collector output is grounded. When measured temperature back to Tmin/Tmax range OC become disconnected and warning diode is OFF.

If the temperature is higher than 45 degrees Celsius, WARNING LED starts to blink but the driver is working normally.

If the temperature is higher than 70 degrees Celsius, WARNING LED is ON and the driver will not power the Peltier module. Also, the open collector output is grounded.

Click to download The user manual