TEC (Thermoelectric Cooler) semiconductor refrigeration chip control application

TEC (Thermoelectric Cooler) is a semiconductor refrigeration sheet that is widely used for temperature control in various devices.

Fundamental:

Peltier effect: Thermoelectric effect, the phenomenon of exothermic heat when the metal contact point absorbs heat. Generally, the thermoelectric effect of pure metal is too small, so the semiconductor material can amplify this effect. Different current directions will cause the TEC hot and cold surface to switch. A simple understanding is that under the action of an applied electric field, the electron flow can bring the internal energy from one side to the other.

  

TEC's temperature control efficiency is actually not high, especially the need for efficient heat dissipation, otherwise it is extremely vulnerable. Then how to drive the TEC to achieve temperature control. Taking an integrated TEC control chip as an example, the TEC's drive control is actually similar to the motor drive. The integrated chip is the MAX8520 with a drive current of 1.5A.

Application block diagram:

Internal principle of the chip:

Chip external PID control:

The figure above shows the principle of the control system. The maximum output current of the TEC is set. The output current is sampled by the sampling resistor and the set voltage is controlled by the error amplifier to control the constant current. The analog PID control circuit here determines the control response and stability characteristics of the entire temperature control system. Simple serial analog PID control, followed by a special description of the analog PID control circuit.

Feature introduction:

PCB design points:

summary:

The above is an example of an integrated chip that briefly introduces the control application of TEC. The focus is on the feedback control design and PCB layout design of the PID. The design of the PID refers to the design case and then can be debugged according to the sample result. The layout design of the PCB should be focused. Consider the problem of isolation, heat dissipation, and EMI of high power circuits.