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TPS54560 heat problem

Jim Reagan
Prodigy 60 points

Other Parts Discussed in Thread: TPS54560

I used WEBENCH to design a 24.5 volt power supply.  VinMin=37V and VinMax=58V with a max out of 5amp (typically drawing 2 amps).  I built up using suggested parts & layout.  The suggested inductor and schottky diode get hot after some time( drawing 1 1/2 amp).  The simulated thermal pattern did NOT have those parts listed as a temperature issue.. 

Anyone have an idea?

Thanks,

JR

  • 0
    TI__Prodigy 240 points
    Jim,
    We need to know a few more details to help address your issues.

    What is your ambient temp that your board is running at?
    What is 'hot'? I did a default design with your input and the IC is going to be about 69C above ambient , and the diode will be +40C (or 89C and 70C at 30C ambient).

    Did you keep the copper areas the same on your board? Same copper weight (2 oz recommended per layer)
    Did you use the BOM as recommended by Webench?
    We need to identify what design you used to build your board. Can you upload your design report so that we can validate your design?
  • 0 in reply to Richard Levin
    Prodigy 60 points

    I solved the problem!  I redid the circuit board with more heat sink area and similar to the suggested layout. Now no more heat problems..

    Thanks,

    Jim

  • 0 in reply to Richard Levin
    Prodigy 60 points

    OK, still have a heat problem, but it is the inductor that get very hot after an hour or two.  Using the TPS54560 with 55 volts input, designed for 24 volts out at up to 5 amps.  However, we are only drawing 1.25 to 1.5 amps.  I have a similar layout and both board layers used as heat sinks.  The TPS54560 runs OK temperature wise.  The inductor is the only heat problem.  I'm using the PM2110-390-K-RC1421.  I've also tried the larger current version with the same result.  The design is straight off the web bench BOM and schematic.  Ideas?

  • 0 in reply to Jim Reagan
    TI__Prodigy 240 points
    Jim,
    Did you follow the layout recommendations? Did you export the PCB design? Did you run any thermal simulations? Are you using a 4 layer PCB, and what copper weight did you use for each layer? A majority of the heat is in the IC (over 2.5W). Second is the Diode. The inductor is not dissipating that much, and is possibly co-heating for other components.

    It would be best for you to let us know what design ID you used for your basis of your design, so that we can corroborate against what we see. Also what Diode are you using?

    -Richard
  • 0 in reply to Richard Levin
    Prodigy 60 points
    Please send me you email address and I will send you actual photos of the power supply. 2 ounce copper. two sided board, lots of copper and VIAs. TPS54560 has no heat issue, nor the diode. All from Web Bench design. Client wants to go into production soon. Thanks, Jim
  • 0
    Prodigy 60 points
    I'm sending a picture along, as well as the Web Bench design.  My client wants to go into production, but we have a heat problem.
    As I said the only heat problem is with the inductor. 
    Thanks,
    Jim Reagan

  • 0 in reply to Richard Levin
    Prodigy 60 points
    I still have no answer or solution... I sent you data this morning. Please contact me directly. jimreagans@gmail.com I need answers SOON!
  • 0 in reply to Jim Reagan
    TI__Prodigy 240 points

    Started replying directly to Jim.  Looking at probably layout related issues (noise) as the root cause.