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DRV135: Heating problem

user6381907
Prodigy 40 points

Part Number: DRV135

Hi, 

We used DRV135 in our design and I attached the schematic. For test the thermal performance, we add the output load resistors, these are used only simulation the end user. We have 2 type of usage, one is differential output and the load is 150 ohm, and the other is single ended with 600 ohm load. When we observe the temperature the DRV135 at room temperature and unboxed board. we saw the differential output version is about 90 C and single ended version is 120 C. These temperature values are too high for a unboxed free air medium at 25 C. Do these values normal for the DRV135? There are no exposed pad and to cool the IC is very problematic. Please check on your side and inform me , if is there any mistake on our design. And also could you please confirm me that DRV135 is fixed gain of 2? Am I right?

Best regards 

  • 0
    Genius 3945 points

    A 150Ω load is too much for the device. It's specified down to 600Ω. 

    What package are you using? SO8 is not recommended (per the data sheet) for "extreme load conditions."

  • 0
    TI__Mastermind 28635 points

    Hello,

    Yes the DRV is a fixed gain of 2 (6dB).

    Regarding the thermal performance, the difference in thermal resistance and packages can be seen below. 

  • 0 in reply to Andy Peters
    Prodigy 40 points

    Dear Andy Peters, 

    Thank you for your response. Yes, we use SO-8 package. But, single ended 600 ohm load line is also very hot. Do you have any idea about that?

    Do you recommennd another package or another IC for the 150 ohm loaded lines?

    Best regards

  • 0 in reply to user6381907
    TI__Mastermind 28635 points

    Hello,

    In my last response you can see the thermal resistances for each package. The SOL-16 package has 80 degrees Celsius per watt temperature rise. This is 70 degrees C per watt better than the SO-8 package. You can calculate the temperature rise above ambient temperature by determining the max load current delivered + Iq that you are supplying. These two currents combined we can call Imax. 

    Your supply voltage across the package is 24V. 

    P = Imax*V= Imax *24V 

    Then multiply the resulting number for your total power by the thermal resistance theta JA to determine the temperature rise above ambient temp. The SOL-16 has the best thermal performance. 

  • 0 in reply to Chris Featherstone
    Prodigy 40 points

    Hello Ghris, 

    Thank you for your answers. Best regards.

  • 0 in reply to Andy Peters
    Prodigy 40 points

    Dear Andy,

    Thank you for your reply, but we use the driver also single ended 600 ohm load. But driver is also warm up to 110 C at room temperature and free air unboxed medium. Also does this situation is normal?

    Best Regards

  • 0 in reply to user6381907
    TI__Mastermind 28635 points

    Hello,

    The device will heat up above ambient temperature when loaded. The temperature rise will depend on how much output current you are driving in combination with the total supply voltage across the device. With these two parameters known, the expected temperature rise above ambient can be figured out with the above thermal equations. The output current can be determined by the max Vout across the 600 ohm load.