Problem with Webench Simulation for LM2678-ADJ

Tony Philip

Other Parts Discussed in Thread: LM2678

Hi,

I created a simulation for the LM26678-ADJ Buck IC, but the simulation temperatures are way off!..it shows about temperature of 200DegC+ for the PCB TOP.

The link to my design:http://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=B71299D44C2818EB

Pls do have a look.

Thank you.

Tony

over 10 years ago

0 Jonathan Arzadon over 10 years ago

TI__Intellectual 1825 points

Hello,

Thank you for bringing this issue to our attention. We will look into this issue and will let you know what we find.

Best Regards,
Jonathan Arzadon
Applications Engineer
WEBENCH® Design Center
Texas Instruments

0 Jonathan Arzadon over 10 years ago in reply to Jonathan Arzadon

TI__Intellectual 1825 points

Hi Tony,

The issue is that the heat sink is not being properly modeled in the WebTHERM simulation. We have already identified why the correct heat sink model is missing, and are currently working to fix this.

Hopefully this clarifies things for you.

Best Regards,
Jonathan Arzadon
Applications Engineer
WEBENCH Design Center
Texas Instruments

0 Tony Philip over 10 years ago in reply to Jonathan Arzadon

Intellectual 260 points

Hi,
so does this mean that the temperatures of the LM2678 IC without the Heat Sink corresponds to the values stated?

If that is the case then it becomes impractical and unusable . Is it not?

0 Jonathan Arzadon over 10 years ago in reply to Tony Philip

TI__Intellectual 1825 points

Hello,

Yes, that is correct. The design would would not work without a heat sink, since the IC Tj would be beyond the operating maximum.

Regards,
Jonathan Arzadon
Applications Engineer
WEBENCH Design Center
Texas Instruments

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Problem with Webench Simulation for LM2678-ADJ