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L6926 - Thermal Shutdown

Question asked by savanth.anand on Aug 17, 2012
Latest reply on Mar 8, 2013 by grimaldi.vincenzo
Hi,

I have tested over 20+ boards that was designed to take L6926 regulators and find that some of the regulators abruptly go into thermal shutdown mode. I think it is thermal shutdown because it tries to spring back to life, heats up and shuts down again in a matter a second. The same repeats when the chip is powered up after allowing a certain cooling time. The currents being drawn from the regulators is only a few mA (10mA max).

After failing to understand this failure, we made provision for a parallel linear regulator. Now, each time we have a failure with the DC DC regulator, we just remove it and mount the linear regulator. The linear regulators have never failed on board. So I am certain that this is not a load issue. I have been seeing these failures over the last several months.

Is there any test method you would recommend for understanding this failure. I have tried using a lower value of inductance (4.7uH) than the recommended (6.8uH) value and the failures are just as common with both inductor values. 

Could you recommend a more stable replacement part?

Thanks.

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