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DRV8432EVM for TEC / peltier

Dear All,

I would like to use the DRV8432 EVM as a TEC driver. I connected the EVM board to two peltier elements - 2 output mode configuration, PWM A OUT and B OUT for one peltier and PWM C OUT and D OUT for the other peltier - (spec of peltier: 48V / 13A / 2,8 Ohm). In addition, I soldered 8 capacitors as described in the manual for the PWM outputs (4x 680nF 1210, 50V and 4x 470uF, 63V)...  

Everything is operating OK, however, I cannot achieve output currents higher than 4 A per channel... I am operating the EVM in mode 1 and 4. In both modes the result is the same.

I am missing something? What is wrong in my configuration?

The power supply is 48V/15A...

In addition, when I change the peltiers for resistor of 1 Ohms, I get even lower current...

Thank you!

BR,

Uros 

  • Hi Uros,

    How are you determining 4A per channel? Are you using a current probe, or reading the current from the power supply?If you run only one peltier does the current double to 8A?

    From your description, it sounds like you may be exceeding the cycle by cycle (CBC) limit of the device.

    You can confirm this by checking both the FAULTn and OTWn pins when running. If neither of these pins go low, this is an indication that the CBC limit is reached. If you are PWM'ing PWM_A and holding PWM_B static, you will need to pulse PWM_B to the opposite state. Once PWM_B is pulsed, the device should begin operating again.

    Please refer to post http://e2e.ti.com/support/applications/motor_drivers/f/38/t/133322.aspx?pi239031349=2 for more details.

    Also please keep in mind that the device is designed for a 14A continuous, 12A peak total. If you are running both peltiers at 100%, this would be 26A continuous.

    If this does not solve your problem, please provide more details on your procedures. What PWM duty cycle are you running? Can you provide scope captures and schematics?