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LMR62014 Power Dissipation

NY
Expert 3040 points
Other Parts Discussed in Thread: LMR62014

Hi.

I'm using WEBENCH to design LMR62014 (as attached). 

The result shows Total Pd=0.71W. However, According to D/S, P(Max)  can be calculated with this formula, 

P(MAX) =(TJ(max) - Ta)/ θJA = (125C- 90C (required TempC))/ 265= 0.13W.

Even if in the room condition like 25C, P(MAX) = (125-25)/265=0.38W, so Pd=0.71W is over the allowable Power Dissipation.

Would you please take a look attached WEBENCH result and give me some advice if my calculation is correct or not.

Best Regards

Naoki Yada

4643.LM62014 Ta85C.pdf

  • 0
    TI__Genius 15810 points
    Hello,
    The Pd number of 710mW is for the entire systems power dissipation. The number you have calculated is for the IC's power dissipation. Your webench report says that the IC's power dissipation is max 475mW. This number is higher than what you calculated because Webench would possibly be using a little different ThetaJA number. The ThetaJA number would be dependent on the board size and amount of copper used. I hope this helps clarify things.

    Regards,
    Akshay