• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 62 subscribers
  • Views 476 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5088MH-1EVAL: Temperature Rise

JDJ
Expert 4636 points
Part Number: LM5088MH-1EVAL


Hello, 

We are running the LM5088-1 EVM with a 36 to 44 input and a 26V output at 2A. From webench these parameters results in only a 177.44mW of power dissipation, but the part  temperature is rising to 43.2 degrees C. The thermal resistance for either the junction to ambient or junction to case should result in a lower temperature rise. Do you think 43 C is piratical for this implementation on the EVM? 

Another issue is that other EVMs are rising higher to 70C. Why could there variation between the EVMs with the same setup and are there any steps to isolate the issue? Could this be because the connections are not well made? 

Webench

Thanks!

  • 0
    TI__Guru 74315 points

    Hello

    Where and how are you measuring the temperature?

    If you are looking at the controller temperature, it is best to use a thermal camera to estimate the junction temperature.

    Most of the power in the controller is from the gate charge losses and some from the Q current of the device.  You should

    be able to calculate the expected power loss in the controller and use an estimate of the thermal resistance to get an approximate

    value for the expected temp rise.

    Also, FET and diode will get much hotter than the controller and will tend to heat it up as well.

    Thanks

  • 0 in reply to Frank De Stasi
    TI__Expert 4636 points

    We are measuring the temperature at the GND vias with a temperature sensor. 

    Using webench, the expected power loss is 177mW. The thermal resistance from junction to case (bottom is 6 C/W which equates to 1 degree change. If using junction to ambient thermal resistance of 40 C/W then that equates to ~ 7 degrees change. These are done at room temp (22C) and the recorded temperature is 43 C on "good" runs with the worst runs being 70 C which is a 20 degree change. This does not match the expected temp rise. 

    Do you believe this calculation is accurate? 

     

    Here is my webench as a reference. 

    https://webench.ti.com/power-designer/switching-regulator/customize/25?noparams=0

  • 0 in reply to JDJ
    TI__Guru 74315 points

    Hello

    Working through email

    Thanks