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What if the ambient temperature is 60 degree C for TPS54295 based design

Aung Thet
Prodigy 195 points
Other Parts Discussed in Thread: TPS54295

We have used webench to generate the attached report for a design using TPS54295 it worked at Ta = 30 degree C alright, however, when I tried to change the ambient temperature to 65 degree C which is the actual temperature of our kitchen product which includes a heater, the webench can't generate a solution for it.

Does that mean we can't use this TPS54295 based design in 65 degree C environment?

Regards

Aung1007.DCDC2ch.pdf

  • 0
    TI__Guru**** 191445 points

    Webench...I looked at this and who knows how webench works.  I'll use 853 mW power dissipation for the IC

    For an 65 C ambient, that correlates to junction temp of 105 C for PWP or 95 C for RSA package.  It really all depends on your PCB layout though.  The thermal parameters in the datasheet are based on JEDEC standard coupons.  A well designed PCB can usually do better.  For a maximum allowable operating junction temperature of 150 C. it looks like you have quite a bit of margin.  I'll forward this to the webench team.

  • 0 in reply to JohnTucker
    TI__Expert 3085 points

    Hello Aung,

    I did the design today for your Vin/Vout/Iout conditions for Ta=60 degC. It worked fine and produced results which are expected. Please give it a try and it should work.

    When you do a design for Ta=30degC resulting Tj = 65 degC. When Ta = 60 degC, we expect Tj to be approximately 95 degC, and this is what I see when I do the design.

    Please see the attached report.

    Surinder

    6136.webench_project_TPS54295_60degC.pdf

  • 0 in reply to Surinder Singh
    TI__Guru**** 191445 points

    That agrees with my hand calculation as well.  For a well designed PCB, you should expect 95 - 105 C junction temperature.