• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 64 subscribers
  • Views 448 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.

TPS62180 Thermal Resistance

Hirotsugu Kobayashi
Mastermind 9540 points
Other Parts Discussed in Thread: TPS62180

Hi, all.

I try to estimate the junction temperature of TPS62180 by following condition.

12Vin 3.3Vout 6A Efficiency=90% Ta=25C

When loss is estimated at 1.72W and θ ja is calculated by 61.5 ℃/W, the junction temperature closes beyond 125 ℃.

But I think that it doesn't become such high temperature in EVM.

Is the value of θ ja right?

Best Regards,

  • 0
    TI__Guru**** 191445 points
    The TPS62180 thermal parameters are modeled values based on JEDEC standard coupon. They are useful for direct comparison of ICs as the models are based on the same standard. Your actual thermal performance may be better if you optimize your PCB design. I ran your parameters in webench thermal simulation. the standard calculation in op-vals showed 70.4 C Tj with effective theta j-a =n2.5 C/W. Webtherm calculated Tj = 76.5 C and theta j-a = 25.8 C/W. That is based on the TPS62180 EVM design with 4 layer pcb. This probably represents the best case performance. Your actual performance will depend greatly on PCB design.
  • 0 in reply to JohnTucker
    Mastermind 9540 points
    Thank you John.
    I'm checking it already in Webench, too.

    Which value is right of θ ja, Webench or a data seat?
    I think the JEDEC substrate will be usually the heat resistance value small more than EVM.

    Best Regards
  • 0 in reply to Hirotsugu Kobayashi
    TI__Guru**** 150900 points
    As John explained, the Theta JAs are different. Theta JA is very board dependent. You should read this app, found right under the thermal table in the D/S: www.ti.com/.../spra953c.pdf

    As well, there is a thermal picture of the TPS62180 EVM in its UG: www.ti.com/.../slvua93.pdf

    Finally, when doing the loss calculations, be sure to remove the inductor losses from the total losses as these are not dissipated in the IC.
  • 0 in reply to Chris Glaser
    Mastermind 9540 points
    I thought Theta JA of a JEDEC board was best case.
    Therefore I thought it became worse on the actual print board.

    Thank you for your answers.