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DRV8332: The thermal pad of DRV8332(HSSOP) has lower temperature than the plastic case

Part Number: DRV8332

Hi Team,

We have received this inquiry from our customer,

We're having some problems with the DRV8332 (or not necessarily problems, but might lack some understanding, so hope you might be able to assist). We've been testing the DRV8332 (HSSOP) without a heatsink, and we're struggling to understand thermal data. See attached an image captured with our thermal imager. Notice the ~30°C difference between the thermal pad and plastic body. Running to motor up and down we've managed to get the plastic body up to 90°C, with the thermal pad still at ~20°C. This seems unusual. Why is the thermal pad not heating above ambient (room is roughly 20°C with no airflow) when the device is clearly generating significant heat. It almost seems like the thermal pad is not connected to the substrate? We've repeated this test on multiple devices, all behaving similarly.

We measured the temperatures using thermocouples as well to verify the imager data. For this particular instance the thermocouple mounted to the thermal pad was around 20deg and the one on the plastic case around 45deg. The thermal imager (as per the photo) measured around 20deg and 50deg for the pad and plastic case.

Regards,

Danilo

  • Hi Danillo,

    You may want to consider that a reflective material like bare metal may have a different radiative property versus plastic. This can cause a thermal camera to show a shiny surface (the thermal pad) as "very cold" since it is reflective.

    It sounds like using a thermocouple may give similar results. Make sure the thermocouple is fixed to the thermal pad (and plastic) with a thermally conductive adhesive.

    You can try this at a much low power so that the device temperature is lower (<50C): use your finger to feel the temperature of the thermal pad. Be careful because if the part is too hot you could burn yourself.

    The DRV8332 die is sitting directly on the thermal pad (upside-down in the package), and so that is the only real path for heat to go out of the IC.

    Thanks,

    Matt

  • Hello Danillo,

    Do you have any additional feedback on this thread?

    Thanks,

    Matt

  • Hi Matt,

    Thank you for the follow up. We didn't received any response from our customer after several emails. I will now resolved this thread. Thank you very much for your response to this inquiry.

    Regards,

    Danilo