Design Description

This design uses the AFE539A4, smart analog front end (AFE) with an integrated state machine and analog-to-digital converter (ADC) to control a thermoelectric cooler (TEC) with a buck-boost (DC/DC) converter. A TEC is a resistive element and is current controlled. The temperature of the TEC element is altered by the magnitude and direction of the current. The TEC element is connected across the VIN and VOUT pins of the DC/DC converter, and the temperature of the element changes as the voltage on the VOUT pin of the DC/DC converter is modified. A resistive network of three resistors is connected to the VFB pin of the DC/DC and the VOUT pin of the AFE539A4 to modify the output voltage of the DC/DC converter. The voltage drop across the TEC element changes as the voltage at the VOUT pin of the buck-boost converter changes, which allows current to flow through the resistive TEC element. The integrated state machine on the AFE539A4 is configured as a proportional-integral (PI) controller that senses the temperature with the internal ADC and adjusts the DAC output to maintain the desired temperature on the load being heated or cooled by the TEC element. This circuit can be used in automotive cooling, portable refrigeration, laser diode cooling, and electronics component cooling.