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LMD18200 Thermal dissipation capability

Bryan Grody
Prodigy 10 points
Other Parts Discussed in Thread: LMD18200

Hi!

I have an LMD18200 H-bridge switch that when it reached 64°C would not switch in the positive voltage direction. The part became really hot as seen with the conformal coat turning a brownish color. My question at what temperature could this part have reached? I know the datasheet says all outputs turn off at 170°C  and all the outputs did not turn off in this case but could the thermal shutdown circuit have failed?

Thanks!

  • 0
    TI__Expert 3920 points
    Hi Bryan,
    Check the thermal flag output to see if it is hitting thermal limit.

    Also, check to see if there is any excessive current going through any of the pins. A case temp of 64C should not be causing thermal shutdown, since outputs turn off at 170C junction (the device temp is still far from this).

    I would also probe the pins and check that the voltage waveforms on each pin looks reasonable.

    Tim
  • 0 in reply to Tim Reyes
    TI__Genius 9645 points
    Hi Tim
    Do you have any thermal solution about LMD18200?
    This chip in my customer's circuit has thermal problem, they want to know is there any solution with this problem?
    Thanks
    Star